You'd have to check with the EFDSS, but I suspect that if you're an individual member it only covers you as in individual dancer or musician, not as a promoter. Organisations can join and get cover for their activities - I'm involved with Poynton Ceilidhs which gets PLI through EFDSS in this way.

It's easy to assume you won't be liable, but accidents happen. As a musician, someone may trip over your instrument case and get hurt. It's not just personal injury, but damage. I was once in a session when I tripped over an instrument case coming back from the bar and caused irreparable damage to someone else's expensive instrument.

As a promoter, you may be held responsible for health and safety issues surrounding how the event is run, as opposed to H&S surrounding the fabric of the venue.

However these things are seldom clear-cut, and in the event of a claim a court may hold that liability is shared. The venue wants to make sure that you are covered for your share.

Just because it's "folk", or because you're doing it as a hobby or on a not-for-profit basis, doesn't mean you're not liable. Just because you don't have PLI doesn't mean you aren't liable, it just means you aren't protected.