Hi not posted here for a few years and started to read this thread but there is too much to go through it all. So I might be repeating what had already been said.
It is wrong to judge the state of Folk Music in the whole of the UK as it is very different in England and Scotland and Wales and Ireland.
From the Scottish perspective up in in Perth in particular it is vibrant. The standard of musicians is high and even in Perth alone there are several great venues which welcome performers. I could go to a session almost every night of the week within a 20 minute drive .
Other genres are also available. ..
If passing through try The Twa Tams or Greyfriars both in Perth. Just down the road in Bridge of Earn is a secret little bar the Cyprus Inn. Worth a visit. And of course bring your voice or instruments.