I thought I'd change tact a little with this blog and rather than a chronology, tackle it in 3 unique parts.

As you know we are making this trip up as we go and so we book accommodation on the fly, mostly using AirBnb, which has been good. So in Bordeaux, we requested a booking in Barcelona but hadn't heard anything before we had to jump on the train to head there. No big deal, plenty of time, after all its a 7hr journey.  You already know what's coming don't you! We arrive in Barcelona, its 6pm and raining and we have nowhere to sleep and I have 2 cranky teenagers and a very tired wife. 
We bailed into the station brasserie which had free wifi and hit the web, and after an hour of intense keyboard work we found a nice "instant book" place in a good area and locked it in for 3 nights - all is good again with the world.
Having learned our lesson we then book our next couple of locations in advance - a week ahead should do it, locking in Nice and Rome, we have 2 days spare which we thought we could go into Provence.
So in the morning I head back to the train station while the rest have a sleep in, and book our train to Aix-En-Provence. Well, all I can say was that was a unique experience. There was 3 possible queues to join: 
1 - information
2 - Advanced ticket sales
3 - same day travel ticket sales
So, which one would you pick?
I opted for the Information queue as it was shortest, and after 5 mins of no movement and attempting to translate the signs, figured I should be in the ticket sales advanced queue given we were going to travel in a couple of days, however the queue is massive. So i sneak into the top of the queue and quickly ask the person what to do. Here's where it gets banal.
She says, I need to get a numbered ticket - a bit like getting a number at the woollies deli counter. No sweat, that's easy enough, except that there are 3 buttons to press. So I press the most worn button. I get ticket E182, I look up to the board and there serving E107 - b*****. I go back to the machine and press all the other buttons, bingo - I get T028 and their serving T027, hit the jackpot,
and before you know it Im back to the window with the same lady and she asks for my telephone reservation docket number - b*****. Ok, back into the queue. No big deal, burned about 10 mins so far.
So while Im waiting I figured I'd jump into the "same day ticket sales", might get lucky there, after all the right queue was only now serving E108. So after another 15 mins there I get to the window in that queue and a very helpful gentleman then told me the process. 
 First, go to the information queue and see if if can get onto the train that you want, then get a number from the ticket machine and queue in the advance sales windows. Wow, mould have been good to know this half and hour ago. No matter, I already had my ticket and they were now serving E123. By my calcs I might make it back for dinner!

After almost 3 hours, and having to deal with a grump old guy who spoke more like a teenage boy (mono sylabic grunts, whose only english was "its not possible", I get it sorted, we sort of. We have our reserved train tickets to Narbonne, but will have to book the rest of the journey to Aix En Provence when we arrive in Narbonne as the spanish cant book french trains (although the French can book spanish trains), which after pointing out the inequality to grumpy, didn't make things any better (yeh dumb I know).
So, All is good, right? Wrong, after much scouring and enquiries, we are unable to secure any accommodation in Aix or Avignon or Marseille on 15&16, so we end up extending our stay in Barcelona by 2 days, which is fine as there is loads to see and do. However it does mean another trip back to the train station to rebook my tickets to Nice! At least I know the process now, and after a short wait (went later in the day) and €200 later even with a Eurail pass, it was fixed, again only to Narbonne and then we hope we can get onto a train connection to Nice. 
Our exit from Barcelona was reasonable smooth, and arrived in Narboone as planned and managed to get reservations onto the next train to Nice, via Marseille where we change trains for Nice. We grab a quick bight to,eat and head to the platform. The train arrives 15 mins late, as indicated on the departures board. We find our carriage and seat numbers, get on board and sit back for the 6 hour journey. After the first stop, some people get on board and have the same seats allocated as us, which was a bit strange, no matter there was plenty of seats. We were due to arrive in Marseille at 3:45, at which point we all got up, grab our bags and went to get off the train. I asked on of the other passengers if this was Marseille as there were no signs, only to discover that we were in Valance, heading to Paris! F&@#. Now what. 
Off the train, to the ticket booth, she'll out another €130 to get back to Marseille, in time to catch the regional train to Nice, not ideal but atleast we can get there in the day. This time it all goes ok, and we manage to catch a bit of luck, as the original train we should have been on was running so late that we were able to meet up with it in Marseille in time to jump on and arrive in Nice as planned, al be it a little late.
now that was one part of this trip I hope we don't ever get to repeat.