"
A folk club near me always puts the guest on First, the. Afterwards the evening becomes a singers night! "

That's a format that I have heard of in "nu folk" venues but haven't come across in the classic folk scene.

There is no way you can give guest night floor spots to everybody who turns up on a singers night. The worst case I have known was an MC whose mates, who never supported singers nights, regularly rolled up on guest nights only after 10:00 and still got a spot with the paid guest doing about 20 minutes instead of 45

Singers clubs and guest booking clubs have different aims and mixing the two can lead to problems like the OP's. Separating into distinct "guest club" and "singaround" events seems beneficial as they can be promoted as separately and there no automatic expectation for the former to give floor spots to every singaround regular.