I have done before, but the airfield is owned by the Army (they were ok with me, but I think that was partly because I used to be part of one of the gliding schools, which are ATC VGS units). Speak to the G5 unit, seem to have lost the number, if you are going to land at the weekend, also speak to one of the schools - 625 or 621, you will need to ring before the head to the airfield, the brief used to be carried out around 0800hrs cet, so the would be in the hangar.
Hullavington is a good size airfield, but wasted with me as I arrived in a helicopter!