Bryan, don't think twice about it, just book it. The Vendee is a great place and the people are friendly. The first time we went to France, we went to a site at St Giles de la Croix but I wouldn't recommend it as it was very commercialised.
After a few days we found another site in a forest by a lake about twenty miles away. I can't remember the name of it now but we found it through the local tourist board who were excellent. There is also a theme park in the area which is more history based than pure fun which you might enjoy called the Pou de Fou or something similar. They had a brilliant gladiator arena which put on a great show with lions and Roman slaves etc. Fantastic. I had a close encounter with a vulture there also which is perhaps best forgotten.
The last time we went in July and the weather was fabulous. Think of warm evenings, with wine and the best steak by the side of a lake. Great. Couldn't ask for more. Incidentally we had only managed to get ten days off work that year and we seriously thought of breaking a leg or arm so we could stay longer! Didn't bother in the end. Let me know how you get on. Roz