The Princess Pavilions and gardens are right on the coast in Falmouth and have a long history in the town, they were under threat to be closed down at one point but thankfully were given a lick of paint and now host regular events.
You have the main event hall where they host theatre productions, bands (the sound quality is not great but i've still seen some fantastic bands here), fayres and even the Cornwall film festival. Then there's the main bar and seating area where they often have low key jazz bands etc playing, outside are the large grounds and main pavilion where in the summer on sundays they have brass bands playing.
We go to the Pavilions a few times a year to see bands (more high profile bands are getting booked), just drop in for a sunny drink (it's great on breezy days as the grounds are sheltered from the wind) or to go to the Fantastic Fal Beer Festival hosted here every october, I can't recommend it enough!
Also, if you go down the back there are the fox rosehill gardens which are really characterful with a kind of grotto you can walk down to. read more