PJ, get in touch for when you are in the London area we live close to Liz(I suspect we might be the OTHER address Liz has in mind above!!!!) I can supply references!! ask Big Mick (he will probably mention Hip Flasks!)and as I work P/t I often have afternoons free to act as "Tour guide" if needed.
I note you will be in London on Tuesday 24 June, a vist to Sharps Folk Club at Cecil Sharp House might be a good start? It is usually a singaround ( sort of like what you call an open Mike)where you sign in to sing as you enter and get called on in your turn, sometimes 2 times one in each part of the session.