Use Camping Cheques and stay at Chateau du Gandspette between Calais and St Omer at £13.95 per night for two people, car and caravan, awning and electricity. It's a lovely site with a nice bar and restaurant, good clean sanitary facilities, particularly in the new part of the site, and very friendly owners/managers. We stay there at the end of each holiday and have a meal in the restaurant for our last French meal.