I've just bought this RaceFace ISIS crankset & rings:

http://www.chainreactioncycles.com/Models.aspx?ModelID=3307

and I've got a 2002 Cove Stiffee frame. Does anyone know what bottom brackets will fit? Is there anything I should avoid? Also will I need a special tool to fit it, as my LBS is chokka and won't be able to fit it for about 2 weeks.

I would assume your Stiffee has a 68mm BB shell. Measure it to make sure, it'll either be 68mm of 73mm but it's likely to be the former

IMO there is only one choice for ISIS BB's and that's the SKF. You can get them from Stif and the cheap BXC-300 will be fine, it's about £40.

RF ISIS cranks want a 113mm axle and FWIW i run a Raceface Turbine on an SKF BXC-300 and it's excellent

Oh, if you go with the SKF you'll need the 8 prong XTR BB tool to fit it

Cheers mate.