How to turn my bitcoins into legal money
Bitcoin acquired through mining are treated as income and subject to Income Tax at the appropriate rate (perhaps 40% if you also have a highly paid job). You'll need to declare this income in sterling equivalent. I believe you'll also be subject to NI contributions on those Bitcoin earnings.

If earned Bitcoins subsequently increase in value, I suspect the increase will be subject to Capital Gains Tax.

As others have said, employing a qualified accountant would be a sensible action.




HMRC Brief 9 - Bitcoin and other cryptocurrencies