From Cherbourg ferry port exit, follow D116 east, following signs to the campsite (4.5km) which is part of a recreational area which includes an indoor pool, jogging track and beach which is good for windsurfing. The campsite has a small shop from which you can order baguettes and croissants for breakfast the next morning - it also sells wine and some other provisions.
The cost was F69.00 for both of us.