No, I am currently employed by the Civil Service. Tax is deducted from by gross pay by PAYE.
I don't know, it's difficult to say. As guestimate - £2,400 excluding any royalties which are difficult to predict.
You mentioned that I may be able to offset direct expenses for doing the activity, would this be things like travel expenses? e.g. train travel and petrol receipts? I will have to spend quite a bit on train travel and paying for necessary fees, food and refreshments, so I'm assuming I should keep all receipts for these to show as a business expense. Also, accountants can be expensive, how can I go about finding one that will help me maximise my take home pay without charging me a fortune?
I don't quite understand the 'allowance' is there a tax free allowance? What is that?