The train to Lhasa was definitely the most difficult train journey we've done. We quickly started to climb in altitude and struggled with the effects it had on our bodies. We skipped between nausea, light headedness and headaches. We reached 12,000ft by the evening of the second day on the train which is the same altitude as Lhasa. This meant we would get three days to acclimatise to this altitude before we continued to climb to base camp.

The train journey was made more difficult by all the staring people. We are getting so much more rural and people are obviously not used to white faces (oddly it was the Chinese not the Tibetans who stared). We had people stood at the end of our beds for the journey just staring at us. Under normal circumstances this wouldn't have bothered us, but when you feel sick being stuck on a train for 3 days with people staring (and filming us sleeping!) isn't fun!

After arriving and settling into the hostel, we had a lazy night resting (as medical advise suggests) so we'd be fighting fit for our first full day in Lhasa.

We weren't.

We got up early and met Gyamtso our guide for our visit to the Potala Palace. This is the iconic building in the centre of Lhasa that sits on top of a hill with mountains surrounding it. We arrived early and we started to realise that Sarah wasn't feeling very well.

As we crossed the threshold of the palace and walked into a cloud of incense Sarah turned a shade of green, rushed past us all into the courtyard of one of Tibet's holiest places and vomited extensively.

At this point I must point out that we suggested taking her back to the hostel, but she insisted on carrying on. She even claimed that she now felt much better and it was out of her system.

We walked up the hundreds of stairs to the second palace entrance (no mean feat at that altitude!) and into the maze of corridors and stairways that lead us to the main entrance. The palace itself is so ornate and opulent (one gold beam we saw weighed 4 tons alone!). It's also clearly a very spiritual place as the corridors were full of Tibetan pilgrims climbing over each other to get a good view (no word of a lie, literally hitting each other our of the way). The smells of yak butter lamps and incense filled the rooms and the chanting of the mantras filled our ears. Our senses were overloaded with everything going on.

This didn't agree with Sarah.

We managed to complete the tour without too much fuss, but her green complexion rang alarm bells. Tom decided to take her back to the hostel for some food and some rest rather than the planned lunch at the bazaar so we got in a taxi and ordered some bread and water.

After an hour of sickness and an inability for Sarah to even keep water down, we called the guide (who had taken Laura and Sam for lunch at the bazaar as planned) and arranged for us to go to the hospital.

We arrived at the hospital to an empty reception with no one around to help and Gyamtso left Tom to comfort Sarah while he went for help. He eventually found it and we carried Sarah to the next building where help was at hand. After seeing three different doctors in three different departments we finally got the drugs we needed so we hot-footed it to a room full of people on drips and oxygen. We poured Sarah into a chair, and the doctors calmly applied her drip and oxygen through our panicking and within half an hour she was sitting upright and smiling.

Not the most successful way to start a new city, but if it was going to be anyone it would be Sarah!

After getting out of hospital later than evening we decided a relaxing night was in hand with Tom and Laura now turning into bad cop making Sarah eat and drink. Sleeping here doesn't seem to be that easy. It seems quite common to wake up thinking your suffocating, not realising it's just a lack of oxygen. At this point we were pretty sure we were on a flight home to the UK for Sarah to recover. Thankfully the next day she started to look better and we decided to take each day one by one.

So onto a more successful day. Gyamtso decided that on our second day he would take us to the bazaar to do some shopping. It was the loveliest market we've been to yet, selling beautiful jewellery. Laura and Sarah quickly bought up most of Lhasa and were very impressed at the cheap prices.

After lunch we went to see another monastery. The winter months are when families make their yearly pilgrimage to Lhasa. This meant outside the monastery was packed with people who stand then throw themselves on the floor to a lying position. You need to keep your wits about you at this time as it's easy to get in the way of a praying pilgrim!

Inside is just as packed, it is such an amazing thing to see so many people praying in one place. Tibet is definitely one of the most spiritual places we have been on this trip, it's such a beautiful sight to watch.

That night we decided to head out into Lhasa for dinner (our hostel having a limited selection and a tendency to tell you they have run out of something half an hour after you have ordered it). We found a tiny restaurant and were greeted by laughs and smiles from the staff who clearly knew what was coming. Sarah was prepared with her phrase book and our first challenge was finding if they spoke Tibetan or Chinese...Of course they spoke Tibetan but the menu was in Chinese. These are always the most fun meals and Tom is now able to draw what we want as well as Rolf Harris could. The waiter seemed amused but unsatisfied when the animal noises began and so phoned a friend who could translate. Half an hour later we had several vegetable and chicken dishes and were tucking in happily.

After our meal we popped to the shops to get some food ready for the next day. While there we met possibly the funniest child we have ever seen. As a whole most kids you can play with and wave and they love it. This child was having none of it though. When you said hello and waved he literally shot his hand up and pointed at you while scowling. This game continued for some time with the child obviously not finding the situation as funny as us. For those Family Guy fans, he looked just like the evil monkey! He pulled the exact face. Brilliant.

On our third day we left at 9am for our journey to Gyanstse. Our driver Mima really does take it steady and at times we felt like telling him to put his foot down. Quite a change from Mongolia! In fairness Tibet are strict on speeding and police log the times we get to check points so they can work out how fast we have been going. We amused ourselves and our driver and guide by playing 'guess the celebrity' at Sam's request.

After around two hours we were told by Gyamtso to close our eyes. When we opened them we were met by 'Yamdrock Lake' translating to the turquoise lake for good reason. At this point we were at 4794m. The lake is the most holy in Tibet and perfectly named. The colour of the lake was stunning and even more spectacular as it is framed by snow capped mountains, blue skies and crisp white clouds. We took some our favourite photographs to date here. Sam took the opportunity to have a photo sat on a yak while Laura turned down the chance to have hers taken with a red maimed dog (you have to admire these people's creativity).

We drove onto a nearby village for lunch and decided on a Tibetan restaurant. The food was excellent and it was lovely to try some traditional dishes such as barley dough. After lunch we drove onto see a glacier, it was flipping freezing here! The cloud was quite low so it was difficult to see all the glacier, but was at an impressive height.

We arrived in Gyanstse at around 3pm and I can honestly say it was one of the most picturesque drives of my life. The scenery is literally out of this world here. When you look around at the mountains its not difficult to realise how high up you are.

In Gyanstse we visited the Baiju Temple. It's literally plonked on top of a hill! The temple was as beautiful as ever. Even though we have seen lots of temples and monasteries they each seem so different. You can climb to the top of the temple and look out over the city, which is a strange sight. It's a tiny city, but totally flat with mountains all around it.

The next day we set off for Shigatse which wasn't far away. When we got there we went for a wander around the local shops and bazaar. This is the second largest city in Tibet, but still so tiny. You can see a real difference there from the other places we've visited with a lot more poverty. There were so many more people begging, who would just attach themselves to you. One child even took Sarah's bottle of water out of her hand.

After we'd had some lunch we headed to the Ta Shi Po Monastery. We were so lucky as while we walked around we walked straight into a bidding ceremony. We were able to just stand and watch a room full of monks chanting and singing. It was the most incredible sight you could ever imagine.

Our next day was the day we had all been waiting for. The drive to Mount Everest base camp. Our guide suggested we got some things for the kids along the way. So we bought pencils, paper and sweets. At one of our first stops we met lots of children begging, excited we gave them pencils and paper. Unfortunately they didn't quite get it and instead snapped the pencils and started eating them. We soon figured out which kids to give sweets and which is to give pencils too! We quickly found some little girls that started drawing the minute we gave them pencils. It was so amazing watching how happy they were.

The drive that day was out of this world. We got our first glimpse of the Himalayas quite quickly and spent the rest of the drive just watching in awe. It is the most strange feeling looking at something you have been taught about since you were a child. No words will ever be enough to explain what that drive was like.

We drove for the whole day and arrived at the Rombok Monastery at around 6pm. This monastery is the highest in the world and is situated right by base camp and is where we were staying for the night. Because it was the low season and the wind was so strong we were able to drive to base camp. We were very glad of this as it was flipping freezing!!

Our guide suggested we bought prayer flags to put up at base camp. On each flag we put the names of people we care about and tied them up with other flags as a blessing.

It was a truly amazing experience to stand at base camp and look at Mount Everest. There was not a cloud in the sky and we watched the sun set over the mountain. It will be very difficult to top that experience.

That night we went back to the monastery for the night. It had no electricity or running water and was the most amazing little place. From our room we had the most picture postcard view of Everest. And all that view cost us was £4 a night. Pretty unbelievable.

However that night at the monastery was probably the coldest of our lives. The temperature dropped to the minuses and there was nothing that could keep you warm. Even sleeping with 4 layers and a coat felt like you had nothing on! That was probably one of the most uncomfortable nights of the trip where you just prayed you didn't need the loo. It was just a hut outside which had a hole in the ground. We are very used to this by now, but at that temperate you don't want to risk falling down that hole!

The next morning we painfully got ready and tried to regain the feeling in our limbs. We went for a quick walk around the monastery but decided it was too cold to stay outside. We all bundled into the car but couldn't get very far. Even though the car had been warming up for 30 minutes the driver couldn't get the ice off the windows. Top marks for effort on his part, he did try and drive for quite a distance with no vision before he realised we were all sat petrified!!

After many make shift ice scrapers we managed to clear the windscreen and were on our way. It was very surreal driving away knowing that it was over. The weather had been amazing the whole time, our guide kept telling us how lucky we were and how it's mainly covered in clouds. On our way back we met the pencil eaters again and decided sweets were a good plan. Tom and Sarah had about 20 kids bundle them for sweets. It was so much fun just throwing them up in the air and playing games with them. There are so many kids here that you cant help but fall in love with them, they are so beautiful.

We drove back to Shigatse that day and stayed there to break the drive home up. The drive was a very quiet one with us just staring out of the window watching the world go by. There is something very beautiful about the scenery and watching the Tibetan people just going out there normal lives.

Tibet is truly one of the most beautiful places in the world. Words will never be able to explain how amazing it is here. All of us are so sad to be leaving. Although we think Sarah's body will be very grateful for a lower altitude!

Note to all, don't go to Tibet with a cold!!