My sons, both surfers (and the eldest now a kite surfer) love Lacanau Ocean - and have stayed on two sites there - L'Airotel de L'Ocean, and Les Grands Pins - both with excellent facilties. Les Grand Pins is an
ACSI Card site and takes the ACSI card up until 25th June, and again after 12th September - so a pitch for two, with car and caravan (or tent), awning, and electricity would be just 15 euros.
Start with the dates you want - and think about the campsite first especially if you plan to travel during the school holidays. If you can go outside this time then you really needn't book a site. My son has just got on at L'Airotel without a booking. They'd cycled down from Cherbourg over the course of a week and then had eight days at Lacanau surfing. Then select your ferry route appropriately. Start looking for a ferry crossing around October, when prices come out, and special offers are available. The longer western channel crossings are the cheapest - but the western crossings probably more convenient. The Caravan Club can do it all for you - or you can do it yourself. M