Two years ago we drove down as far as Carcassonne - so not too far from your destination.
We had two overnight stops on the way down though - never having driven that distance before. Our DC were 9, 11 and 12 at the time, so were happy to explore different towns on the journey.
We live in W Yorkshire and like to use the Eurotunnel - so we set off at about 3am - inorder to cross before 8am.
We stopped off in Rouen and Limoges to break up the journey. Both times we stayed in Etap 'hotels'. They were fine - as were out of the town, so parking was good (although the Limoges one was more central). Cheap enough - and clean. We had two rooms - one for me and my DS, one for DH and his two DSs. The rooms had a double bed with a bunk above.
I always pack plenty of non-messy sandwiches. Stuff like cheese spread, marmite, peanut butter etc - no salad or fally out bits. I freeze bottles of water and use them inthe cool bag as cool packs - and obv they defrost with time so alway some cold water to drink. I buy packs of cheapo buns/cakes too just to keep kids occupied - and cos they go nice with a strong coffee bought at services.
We bought twin dvd players - but they didn't get used as much as i thought they would. Still worth having though.
I didn't get a toll card - but didn't find it a problem.
My tip is to plan your route using www.michelin.com - you can plot your start and end point - and it costs your trip, and gives you the price of each toll point - soyou know what £ to have ready. It seems up to date.
Last year we didn't drive as far south - we went to the Dordogne - and so broke our journey in Blois. After an early morning start - it is nice to stop somewhere and have a walk around -and a nice dinner. It gets us in the holiday spirit. We stayed in an independent hotel there - as there were just me and DH with th two eldest boys - who were able to share a roomnext door to us.
Just in the process of planning this year's trip. We are staying inthe Charente - so not as far to drive. We will probably stop off somewhere though - just to see more of another town.
Blanket and inflatable pillow each in the car is good (for the kids) - it just lets them sleep a little more easily and stops grumbling... I limit 'hand luggage' too in the car. One small backpack each - or else you have stuff scattered all over. Oh, and no chocolate in the car :)