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

https://www.insert-bookmark.win/a-ukgc-licence-is-the-starting-point-not-the-whole-story-better-platforms

A UKGC licence is the baseline, not a guarantee of a smooth experience. Check for clear, game-level RTP information, realistic withdrawal times and useful responsible gambling tools, including deposit limits and time-outs