Open Question: Where is a good place to go camping for groups of people?(england)?

I want to have a camping party this weekend, if not the weekend after, with roughly 15 people including boys & girls. But a lot of camping sites only take caravans,couples, ar families. does anyone know a place that takes groups of people? preferably not too expensive to book.
It needs to be within an hour and a half train journey from london.
If anyone could help me that would be amazing
thank you x

Source:
http://answers.yahoo.com/question/index?qid=20110703080005AAUSSo9

pirateland campground reviews ocean lakes campground coast to coast tent camping california