"Do agents communicate with their artists?"
A club organiser who I know once received a contract that was pitched at a pop concert with requirements for a private dressing room with fresh fruit etc. She had known the artist for decades and on phoning was told to just put a line through those sections.

Admin fees - HMRC would expect their cut from the recipients. I would be more worried about the arrangement getting classed as employment with a whole raft of regulations to think about.

Agents - its a lot easier to do a single mail out than to customise each one and just because the club room takes 40 doesn't mean that the club doesn't get involved with bigger events either in it's own right or in conjuncton with others.

Which is of course another aspect of promoting the club, be proactive and get involved in local music and arts festivals to put quality folk music in front of a non specialist public and promote the club.

Remember a person doesn't become a prospective new member until:
1. They decide that they like, or at least want to try, folk music
2. They know that there is such a thing as a folk club