I tried Citizen advice but they hardly had any idea, they said I need to register business and have good business plan and them wait for it to be approved. As I don't have business plan I should sit down and think of one. Clearly not very helpful but yes I never thought of calling the tax man himself! of course they will have an idea of what to to and where to go.
Thank you very much
Besides that my employer knows but she never said anything about collecting any tax, I shall double check with her.
Thanks again,
Kasia