Seahouses Community is the website. Has a list of the B&Bs there.
However- I've stayed here before:
Stan Halls B&B (Beadnell)
Farne Diving Services (compressor there too)
The Lodge
Seahouses Community Lodge Page
The Old School House (with the paint still wet when I stayed and owned by Sovereign Diving and has a drying room)
Old Schoolhouse
The Old Ship (brilliant pub and right on the harbour also has the bell from the Yewglen in the bar and all sorts of spidge)
Seahouses Community Old Ship
And last time I went up (a couple of weeks ago and a bit last minute) we stayed at the Purdy Lodge which is a bit of a drive away on the A1 (10 mins) but more of a Travelodge type place
Northumberland Accommodation - Belford - Purdy Lodge
We did 4 cracking dives in the 2 days we were there with Billy Shied's boat (which is huuuuge). Highlight was the dive through the gully on the Kinivestone right through the seal nursery then popping out right on the wreck of the Abessynia. Brilliant. Don't bother taking your twinset- it's a single cylinder type trip all round the islands unless you want to spend aaaages on the Somali (but tides usually stop you from doing that anyway).