Probably the same ones they used for the Briefing. Go to Google maps, type in the post code and 'serach nearby' for B&Bs. You'll find that a few of the nearer ones will be fully booked the nearer you get to your Main Board date. It won't be a drama - more time to get ready in the morning and you can claim the money back.
I used the one 500m up the road, Cedar Lodge Hotel I think - nice enough, although the blokes beeper to tell him the food was done sounded like a smoke alarm which caused me mild concern for my medium rare steak. Crap pint of guiness too.
I stayed at redwood lodge too the night before, sandy came in a bit worse for wear after a few whiskys but she was lovely!
She also gives you all the Thankyou cards and letters to look through over breakfast with handy tips from past board attendees which I found helpful.
I've not stayed before but just booked a stay at the Redwood Lodge this afternoon and have to say Sandy came across as friendly and genial on the phone and was very helpful indeed. The only thing I would say is to book early.
If you get yourself down to Tidworth or Amesbury, meet up with a few of the lads (you'll spot them, don't worry) in one of the drinking holes (you'll spot them, don't worry), let them know who you are and why you're there, I'm sure they'll consider it their duty to help out; you'll be able to access all manner of useful tips, trade secrets, you know the sort of thing. It'll give you a nice edge the following day I reckon. If you go out dressed ready for the following day you won't even have to find a B&B, you can get a taxi straight to Westbury after the session (make sure you book nice and early, and don't forget to get a receipt). Good Luck.
Best one you can possibly get is Redwood Lodge!
Sandy's super friendly and helpful, you get dinner and breakfast, its cheaper than most and she's friendly as hell. Best of all she can even give a few tips. Pretty sure the story is she has two of her boys serving at the moment so she's pretty switched on. Don't bother with the others if you can get in there.
What date are you guys attending ur main bored? Mines the 6th of sept and iv booked the travel lodge at warminster, £45 and only 10 mins away, the main ones in westbury tend to me alot more, plus travel lodge is fine for one night!
I went to Redwood Lodge a couple of years ago after being recommended it on Arrse and I can safely give it 10/10. Food was great, Sandy is a legend and it's nice to stay with other AOSBers. It was great trawling through all the cards and thank yous over breakfast! Puts you at ease (comments such as 'totally screwed up the planning exercise, got my maths totally wrong and still got in!')