If you're wondering about the legality of gambling and using crypto in the UK, you'll be glad to know that as a jurisdiction the UK Gambling Commission certainly does recognise Bitcoin as a legitimate form of gambling currency.
Yes, you could easily get away with registering and licensing from a variety of other jurisdictions like Costa Rica, as suggested by others, but if you're setting up a business and are inclined to go with regulation and reputation, a license from the UK GC jurisdiction is worth far, far more than that of say, Costa Rica.