I went to Tilstock by car one day, to have a Parachute re-packed, and asked them about flying in to their runway. They were quite happy to let me do that, providing it was by PPR, on one of the days when they were open.
Still haven't been there, even though it is the nearest airfield to Sleap. However I have been to Cark, and can confirm that they have the same 'esprit de corps'.