You seem pretty well set, but consider:
Headlight beam deflectors work better than the black masks - you'll be surprised exactly how much light is lost with a mask
If your car has the new Xenon Discharge headlamps - then you can't use deflectors or masks - you will need to ask you garage to set the lights to "symmetric" pattern - this may a lever under the bonnet.
Driving licence(s) and original insurance documents - Not a copy
You've already thought of the proof of ownership for both car and caravan, and the spare bulbs for both car and caravan. Reflective vests are not a requirement for France (only Spain and Italy) but a good idea anyway.
GB Stickers - must be the full sized GB on white background stickers - or if your number plate has the new Euro style "blue edge with country code" then you don't need a sticker on that vehicle.
The new E111 medical insurance cards - go to the post office now - they will take a few weeks to process - free but you need them.
Obviously passport and credit cards - most motorway tollbooths take credit cards - most Hypermarkets take UK credit cards with PIN Code verification - and if you forget anything you may be able to buy it cheaper in France.
Whilst most European camp sites use the blue IP44 electric hook up, a small number of French camp sites use an outdoor version of their mains socket. Go to a camping or on-line and buy a "Schuko" Euro plug to IP44 adaptor.
A good quality map covering your route - Michelin are the best - and maybe a detailed map of your final destination, or a GPS navigation system with French maps.
Plan your route from Calais to EuroDisney with www.viamichelin.com, it's a free service. Write down the major directions (towns, road numbers) on an index card and keep it close to the driver. Allow 5 hours for the journey - excluding stops.
Driving in towns - if you drive through a town and the next town you want to travel to suddenly disappears from the road signs, just keep going straight ahead - often only alternate directions are posted.
Driving in towns - get used to Toutes (All) Directions and Autres (Other) Directions.
Signposts at road junctions - you've stopped at a set of lights and across the junction, you will often you will see a road sign on the right-hand side of the road ahead pointing left (with your destination town on it) - this does not mean turn left - rather the road ahead is the correct road.
But above all enjoy it, traffic density is just like it was in the 80's