Probably not. You could be ejected for a variety of reasons. However, unless the police can be bothered to spoil your fun, you'll probably get away with it. Just make sure you behave responsibly i.e. don't litter the place and make sure you're not disturbing any wildlife or wandering into a SSI. You may also be in breach of local byelaws, so make sure you check out any signs and warning notices.
Oh, and get Acrobat Reader for those handy .pdf files
