Sounds good.
I used a bunk house at a B&B near Talgarth (near Brecon).
It's the Castle Inn,
http://www.thecastleinn.co.uk/
It's a fully heated bunk house and food/B&B were great.
Trekker's Barn
Staying in the Trekker's Barn providing your own sleeping bag or duvet, and towel
£12 per person per night plus optional £3 for full breakfast (all group option only)
I was going to go last year but they wouldn't take a booking just for 1 night.
But i suppose if enough go we can book in and people can stay for as little or long as they like.
I have emailed them to check availability and also see what their minimum requirements to book that weekend are.