Morris dancing etc.
11 The provision of any entertainment or entertainment facilities is not to be regarded as the provision of regulated entertainment for the purposes of this
Act to the extent that it consists of the provision of —
(a) a performance of morris dancing or any dancing of a similar nature or
a performance of unamplified, live music as an integral part of such a
performance, or
(b) facilities for enabling persons to take part in entertainment of a
description falling within paragraph (a).

Sorry Penny you are right and I been reading this stuff for far too long....

You could always argue that (b) would cover and exempt your amplified mandolin or PA...