Judwin are super-friendly with very a pretty good landing fee (I think it was less than a tenner). I visited them mid-week though, but I'm sure they'll be just as helpful at the weekend.
Henstridge was an OK airfield, although when I visited Old Sarum this weekend there is a notice on the board in the Clubroom saying that Henstridge is out of bounds for club aircraft due to the surface conditions. It was rough off the main runway, with a lot of loose stones when I visited but not sure what its like now.