Hi vis for each person in the van. Safety triangle. Headlight beam benders or the VW protectors with the shading on are better as they can be reused and just clip on. Adapter for the cable for our 3 pin to possible 2 pin in foreign parts.
A LiberT tag for the tolls if you are travelling a lot on the motorways is handy to avoid queues. French holidays have started now so it could be busy at the tolls.
Get the All the Aires of France book. Most are free, some good, some grotty but well worth having. All towns and most villages have one. Easy to have a look at them on Google Earth.
Don't buy fuel on the motorways, it's nearly always cheaper to come off and find somewhere. Not as many filling stations in France though so don't run low.