There are loads of really good campsites around, but you need to know where to look. We will add to the list of sites we have personally visited, but in the meantime check out the following links.
Cool Camping - Your camper will have a copy of this great book with loads of really cool campsites listed. So many people want to keep the book at the end of their trip we now keep a small supply so you can treat yourself to your own copy.
London Campsites - Yes, you can camp in London and here are a list of sites from Visit London.