I think this club is aimed more at visitors who go on a regular basis. The ones that have property abroad. The ones that will travel more than once or twice a year.
As for the caravanner who makes one holiday trip a year I don't think there would be any benefit.
Slightly off topic, but a friend of ours has a property in Brittany, and had BF shares etc. for the discount that gave. He has looked into all ways of economising, but still uses Eurotunnel via Tesco for the best deal!
Don't forget to leave a review of the French and other European campsites you have visited!