I've not looked at a map, the Penzance links page lists three options(two as above)

Thursday
The Star, St. Just - Open Mic event in a great pub, from 9pm
Blue Anchor Helston - Round the room session in a great pub. Very friendly. From 8pm
Tinner's Arms, Zennor - Weekly Music session in a lovely old pub. Mainly Irish
get links from their page
http://www.penzancefolkclub.co.uk/Links.htm