For holidays in France, you have to pay the tourist tax when you arrive. This tax is stipulated by the communities and will not exceed 1.50 € per night and per person. Certain owners include the tourist tax in the booking price.
Activities with a charge have to be paid at the campsite as well.
You will also have to pay a deposit for your accommodation. However, this money will not be taken but it will be refunded on your departure under the conditions set by the campsite.