Hi Richard,
We stopped at Chateau de Martragny when we visited in 2009 and I would recomend it to anyone. It's in a great location, just between Bayeux and Caen, which makes it easy to cover all of the British area from this campsite, and also has great facilities.
http://www.chateau-martragny.com/specific/formats/index.jsp?lang=EN
Scott