Well,if you leave a vehicle still long enough ,the battery will obviously deteriorate and possibly leak acid causing corrosion. The fuel will go stale and evaporate leaving deposits in the carb which will later cause problems, the pistons when left static in a bore can even seize with corrosion in a damp environment or leave a mark which can turn into a 'high spot' which can be a problem with creating a hot spot certainly in aircooled two strokes in my experience so quite possibly in 2cv as well , the tyres will start to crack at the sides rendering them weaker when they are put back to use plus they can develop 'bulges' where they have been sitting which can be dangerous and could lead to blowouts.
Doing those things are precautions against all those things and ensuring your car is kept in the best state to reinstate it when you return to it ,obviously not all of those things may happen but the longer it is left the more of them will happen and the worse it would be so in my thinking it would better to be safe than sorry ..

If it was closer I'd offer to start it every now and then

Should have brought it down here Chris, I'd have looked after it for you. Remember not to apply the handbrake, take note of everything Ken has written and what ben has pointed out.

I'll send you a PM regarding something else I wrote here before a moderator deleted it.

Have a great trip.