A UKGC licence is a baseline. Check if RTP is clear, cashouts are quick, and...

https://sofiassplendidblog.inkharbory.com/posts/game-library-size-vs.-quality-do-you-really-need-4-000-slots

A UKGC licence is a baseline. Check if RTP is clear, cashouts are quick, and limits, time-outs and self-exclusion are easy to use