Living in the vicinity of Corby and Kettering, I rent land from Boughton estates for my airsoft company, which means that I get to occasionally have bushcraft wild camps with players before games held on the following day. The estate are very hot on trespassers, and have a large staff of workers who patrol the woods, so I always get permission for such wild camps. It kind of makes up for the exorbitant fees they charge for us to use their land. One thing that I have done is camp on river banks along the Nene or Welland. I carry a fishing licence and a small set of gear, and if required, I pay for a 24 hour fishing ticket, which is about £5, depending upon the club that controls that stretch of river. In my experience, it's usually free. There are literally hundreds of miles of bank.