According to the bill, rather tham Kim Howells, I don't think it is the case that demonstrating an instrument is not licencable. see this clause in part 2 of Schedule 1:

Film exhibitions for the purposes of advertisement, information, education, etc.

5       The provision of entertainment consisting of the exhibition of a film is not to

be regarded as the provision of regulated entertainment for the purposes of
5

this Act if its sole or main purpose is to—

             (a)             demonstrate any product,

             (b)             advertise any goods or services, or

             (c)             provide information, education or instruction



If such as exemption is needed for films, it can only be assumed that live playing is not exempt, even if its sole or main purpose is (a) (b) or (c).