Have you tried folk festivals that feature workshops, or your local folk music/instrument stores?

Lark in the Morning (www.larkinam.com) does a California Bay Area folk workshop getaway yearly... I think the East Coast "Folk Songs Getaway" does classes as well. I've heard tale of others doing similar deals.

The standard pattern seems to be a large amount of people getting together around barely adequate camp areas, holding a number of 'workshops' ranging from wide interest ('Folk in America') to specific ('Bodhrahn triplet techniques'), and then playing great music most of the night while drinking the contents of a couple major breweries. I am pretty sure they have this sort of thing in the UK too. At least, I think I'm pretty sure. Actually, honestly, I haven't the slightest, but I hope they do.

M