Hey, guys, making a living as a folksinger is a matter of recognising that being a performer is operating a small business. I can't speak with authority about working in the UK, but, in the US, there are thousands of facilities that hire folksingers on a fairly regular basis. It takes a little while to get established in an area and, until that happens, it takes advertising, publicity and, best of all, networking. I have helped many performers by introducing them to facility agents, sharing mailing lists and, for out of town acts, recomending them to venues.
The longer one works in a geographical area, the more he is known and the more he is trusted. It's just like any other business, in that respect. OK, here are some ideas you might try in your own home towns. Don't concentrate on clubs and such. That way leads to the kind of noble poverty that you have been experiencing. Look for booking agents that specialize in senior facilities.(In Pennsylvania, resident facilities are required, by law, to provide, at leats, one live performance each month. Many do more and there are hundreds of these nursing homes, retirement communities, etc within a 45 minute drive of my house. I could do one every day of the year and never repeat.) Children's programs are great jobs. People don't mind spending money for their kids and every fair, fete,
boat race, bike race, holiday celebration, supermarket opening is a potential kids job. These jobs are booked through agents and, if you are having trouble finding these agents, perhaps I can help you locate them in your area.

                        Mike