Don't overlook what I said - "CLs run by Brits." There is a book - albeit in French - called Camping a la Ferme which will tell you a lot about the French idea of CLs, whereas anything run by a Brit will be very similar to what we have over here. At least you can be sure of a correctly wired blue socket.
For clarification on that last comment, 2-pin Schuko is wired radially from the power box not in a ring as we have here, and each outlet has its own fuse or MCB. Since anything short of major white goods (which are often three-phase) in the EU is double-insulated with a double pole switch it makes no difference which way round the outlet is wired. Having become used to this electricians just put L & N wires into the relevant holes without looking at the socket to see the embossed L or N. Hence I have stayed on a site (just inland of Boulogne when en route ferry at Calais or Dunkirk) where there were three 2-pin sockets in a line on a board; the two outer were correctly wired (French plugs also have an earth pin so only fit one way) but the middle was reversed. If your caravan has 13A sockets with a double pole switch it isn't a problem, but if it is single pole or unswitched you could have something live when you though it was off under fault conditions. A good idea (which may be disputed) is to take a blue plug and socket with about a metre of cable between and with the live and neutral reversed AT ONE END ONLY. You should also carry a mains tester plug. (Having a metre of cable means you can put the link plug/socket under the van to keep it dry.)
I would also advise that for a first trip don't overdo it. The north coast of France and round the corner as far as Le Havre and Honfleur is very attractive. If you are not a 'coaster' the area around Rouen and SE along the Seine towards Paris has much to offer (such as Monet's Garden at Giverny,) and if you go a little SW of Rouen there are some nice towns (Brionne and Bernay) and you can easily get to Honfleur, arguably one of the most beautiful towns in France. Inland another place worth visiting is Bourges which is very close to the geographical centre of France. Finally I would recommend Alsace, particularly Southern Alsace. There is a small town called Obernai (if any of you know Yorkshire it is like a very old Otley) has an excellent municipal site only 10 mins or so walk from the town centre. You can easily get to such as Colmar, Riquwihr, and Ribeauville all of which are on the Alsace Wine Route, and you can get across into Germany to visit Offenburg and Freiburg and a bit of the Black Forest. Strasbourg is interesting. They have fantastic whole-village Vide Grenier (a bit like a Sunday market/combined street market) all day on Sundays which are always worth a visit.
Belgium is interesting if a bit dull. Ghent is a good base as a starter. In NL Utrecht is also a good base. (Visit Dordrecht - beautiful and near the UNESCO windmills.) I have covered Germany I think.
Good luck.