Hi Simon,
If Ozz is unable to help, I am a partner of a firm in the West End. We do specialise in arts/entertainment (hence I did not contact you initially), however if I can be of any service to you I am happy to have a chat. I believe that if anything the specialism of your business would be around VAT issues.
Although it sounds like you are looking for a fairly fulltime bookkeeper?
Our website:
http://www.breckmanandcompany.co.uk/
Cheers