When you use Camp site search (put in one that you know is listed)and the details of the site come up, at the bottom of that page it says "If you have spotted a Camp Site that is missing please click here to let us know". If you click on that link it gives you the opportunity to add details of a site not previously listed. The site does not appear straight away (I presume some sort of checks/admin stuff must happen) but when it does you can then add a review.
Might be an idea to do a map search just in case its under a different town/village. If you still can't find it do what Bofs has suggested. You do have to wait until its added before you can submit a review.
Hi Bofs, it's usually within a day at most. I think the one you added is already listed, their CL is included in their other listing, they didn't want a separate entry for it. http://www.ukcampsite.co.uk/sites/details.asp?revid=9506 Let me know if this is incorrect
Cheers
Ian