So do you need to pay tax on money gained at the moment? Are regulations coming in?
if you get fiat (£) then you need to declare it and it will get taxed.
it doesnt matter if its from selling a bitcoin, a house or a car.
however selling most cars (common thing many people do) they dont make thousands in profit as most cars decrease in value by hoarding it, so taxmen dont chase you when you sign your log book over to someone else.
however if your making thousands by selling a house or bitcoin and not investing it the same year.. the tax man will chase you.
also dont think that just because they didnt chase you this year you are now free, HMRC can retrospectively chase you in many years time for income/profits you didnt declare years earlier, so dont think about spending all of it if your not gonna declare it... as it may hit you in the future
what most smart people do is this
imagine you bought 10btc last year at £1k each (£10k)
this year you sell just one btc.. thus you have £10k back at this months average..
you have technically not made a loss or profit.. £10k in £10k out.. no tax
now your more then likely to be free to spend that £10k without any tax burden
but if you want to sell all 10btc(£100k) expect to declare it
but speak to a tax adviser about assets