A UKGC licence is the baseline, not a guarantee of a smooth experience. Check...

https://www.bust-bookmark.win/a-ukgc-licence-is-the-starting-point-not-the-whole-story-check-that-rtp

A UKGC licence is the baseline, not a guarantee of a smooth experience. Check whether each game’s RTP is easy to find, how long withdrawals usually take, and whether payment conditions are clear