Really confused by Home Office documents, need some help from real people

I am currently employed as a financial analyst under the Business & Commercial Work Permit Scheme.
My hobby is dancing and I would like to have a possibility to perform sometimes and get paid for it. Not sure how to do it legally.
Home Office says:
The work permit holder may undertake additional work without further permission provided that the work:
is outside of their normal working hours -> works for me
is no more than 20 hours per week -> fine as well
is in the same profession and at the same professional level for which the holder’s work permit visa was issued - here is my problem...
Another thing - "A work permit holder is also not allowed to enter self-employment" - and a freelance dancer can be viewed as self-employed?
So I understand that I need to apply for additional permit, but how to do it and will they allow me to do it?
Thanks a lot!