There's Keith Festival on 12 June - 14 June.

Most of the singing there is of the unaccompanied variety(and there's lots) although there is also a musical(These days, dominated by SDBs unfortunately) side as well.

It's friendly and welcoming though.

The website seems to have gone as it used to be linked to the TMSA site which has now ben revamped.

Ah, I found something.... http://tmsakeithfestival.blogspot.com/