I went to a do a few weeks back which was in a big house with 16 acres and the owners were talking about holding events. They allowed us to camp over in the vans and lots of people used fire pits. They do have two outbuildings which were used for a band them music and also had toilets n showers. It's near Market Deeping in Lincolnshire. I have sent a message to a mate who knows the owners and will see what I get back.