Jack:
Edinburgh is particularly appealing to me because I'm already familiar with the city (I lived there for 3-4 months a few years ago). So you go outside of the city to clubs and have no trouble returning at night using public transport?

I have one question vis-a-vis Edinburgh: most of my research has been on folk music in the US and England, since the two nations have been so historically intertwined in regards to almost all types of music. How much of the emphasis in Edinburgh is on uniquely Scottish or Celtic music? If this is the majority of the emphasis, it might throw a wrench into my project, but perhaps I could incorporate it, I don't know.

As for "class", it tends to be something I avoid--not that it doesn't carry weight with people, but it can be a dubious analytical category since, as you say, job and income are only a small (and often inconsequential, depending on the context) part of personhood. The main thing I'm looking for in searching out folk clubs is people that are highly interested in the music, spending a lot of their lives invested in it. If I can judge by myself and others I've met, that investment is characteristic of many (most?) folk fans.