In the cubby hole inside the step into the side door I fit the following
full set of sockets and spanners
full set of Allen Keys
Tow Rope
Little Air Compressor
Torque Wrench (doubles as a Handy breaker bar)
Some Latex Gloves
Oh yeah, and the standard jack, the jack handle/winch bar thing for the spare wheel, foldy-up wheel chock, shells, rocks, twigs and other bits the kids have collected on the journey.
Check that you have the spanner or whatever that fits on the end of the winch bar to lower the spare wheel...mine didn't have one so I use one of the sockets.
In the cupboard I keep a mini-toolkit with the usual ratchet screwdriver and bits (including torx bits)
Then in an AA zip bag that I stuff between the middle bench seat and the side of the car I cram in a multi-meter, some lengths of wire, couple of paper clips, crimp connectors along with the usual mandatory bits for france like spare bulbs, day glow vests, booze testing things etc etc.
other bits we have that are generally useful are
Anti Mosquito ball things that we hang inside (Mos Away I think they're called but beware the unbranded cheap ones)
A Large Mosquito net we jam around the edge of the sliding door so we can have it open at night (especially when arriving somewhere late with a hot engine warming the place up and not being able to open the door for the mozies)
Fire Extinguisher
First Aid Kit + a small handy one for bags
Hand Sanitizer
Bag packs with water reservoirs
Washing line and pegs (we use little suction cups on a bit of string that stick to the van when there aren't any convenient trees around)
A Torch in the drivers door
The Bongo Service Manual
10 Days in france may not be worth this, but when we go for a month, we get a French Data Sim. LeFrenchMobile did a good one for us last year which was good data prices and also allowed voice calls... (providing you have an unlocked mobile)
have fun !
Ant.