Les - your two-tier idea of a folk club, with a beginners session at the beginning and the proper club starting later, has been done before, I heard with great success. Go for it!

This problem is solved in some other places by the scheme I mentioned before, when the same people run a very informal pub session in parallel with the club. I have actually seen singers start (very nervously) in the session and months later have enough confidence to be able to sing in the club. This is a Very Good Thing, of course.

Anahata