A UKGC licence is the baseline. Check that RTP is easy to find, withdrawal...

https://devinsmasterperspective.opalvector.com/posts/my-slot-site-search-is-broken-should-i-avoid-it

A UKGC licence is the baseline. Check that RTP is easy to find, withdrawal times are clear, and responsible gambling tools - such as limits, time-outs and self-exclusion - are easy to use. These practical details can make the difference.