Have recently returned from the Loire where I stayed at an excellent site south of Saumur. Camping de Courte Vallée, 8 Rue de Courte Vallée, 79600 AIRVAULT, France.
The site is run by an English couple and has a very strong English feel about it – and is about 400 miles from Calais. You could stay there for a few days or use as a transit site on your way south or back home. I enjoyed it.