Before signing up, check the operator on the UK Gambling Commission register....

https://speedy-wiki.win/index.php/What%E2%80%99s_the_fastest_way_to_sanity-check_a_bonus_headline_like_%C2%A31,000%3F

Before signing up, check the operator on the UK Gambling Commission register. Read bonus terms closely, including any 10x wagering cap; don’t trust headline sums. Check mobile usability, withdrawal times, fees and limits before deciding.