I’m not too sure. I think forex is. But again I’m not sure.
https://www.google.com/amp/s/cryptovest.com/amp/news/uk-bitcoin-investors-might-exploit-gambling-tax-loophole/ I believe @Duttydirtz has stated this several times in the icx thread. Worth looking into!
You probably should have lead with the fact you’re in the UK to avoid to obvious confusion. Just be careful about writing everything and anything off. It does sound like things are different in the UK, because it’s been easy for the IRS to see right through those things. Just reasonable thinking is about all we can say from the States.
My two cents would be: if its an example like the one you gave with the “security” dog, lying isn’t going to be the best policy. If what you write off as an expense doesn’t make sense, don’t do it. Crypto falls under that mindset. Good luck with your earnings though!