I would't book to early, best summer deals appear around Feb/Mar. For June you could probly book a couple of days before you leave. We left on Jun 9 and booked one way car/caravan 2am crossing for £55 a few days before. When we want to come home in Sept we shall book a crossing back.
Don't forget to leave a review of the French and other European campsites you have visited!
A day of all things motorhome and campervan. The show is held both in the main indoor arena and across the grounds. Catering, hot drinks and food options are available. Easy access to the site and free parking included. Win one of five pairs of day tickets