We had a nosy round Colerne, Emersons' Green and Corsham at the weekend. The HIC said anywhere within 25 miles of Abbey Wood could be used, which by my calculation, puts Lyneham out of radius (by about 2 miles).
MQ in both Corsham and Colerne were not in the villages themselves - about 1-2 miles away from the traditional village. The MQ in Corsham looked hideous - really grotty private (or possibly council) housing estate with no shops or facilities (though did see a primary school and a community centre). Colerne looked OK - all forces accommodation (no scary council estate) but with a Hive, facilities on the base (including a nursery). The primary school is in the old village - 1 mile away.
Didn't make it to Hullavington but apparently they're quite nice too. Apparently Colerne has a lower grading because of the lack of facilities but the quality of the housing seemed OK to me (modernised kitchens, new carpets in all the ones we peered into).
Emerson's Green - massive civvy housing estate (4000 homes) of which 200 are PFI housing used for MOD accommodation (i.e not MHS). All brand new and shiny, lots of facilities as you're right on the edge of Bristol.
They also use SFA in Long Ashton, Stoke Park and Keynsham but we didn't look at these, though I think Long Ashton and Stoke Park are the same as Emerson's Green (i.e. PFI not MHS!)