"all are welcome to a traditional music session (instrumental and song) at The Pirate, Alverton Road, Penzance, Cornwall, every Tuesday from about 8.30pm onwards. Participants and non-participants welcome!"

(from Newlyn Reelers website)

I've been to this one and while it's not an English music session as such, it's "anything goes" really, and quite fun.

Ask Alan and Linda Collins for further advice.
If you're who I think you are, email me and I'll put you in touch.

Anahata