Before joining a new betting site, check its licence on the UK Gambling...

https://wiki-byte.win/index.php/What_questions_should_I_ask_support_before_I_try_to_withdraw_winnings%3F

Before joining a new betting site, check its licence on the UK Gambling Commission register. Read bonus terms closely, including any 10x wagering cap; headline offers can mislead. Also consider mobile usability and check withdrawal times, fees and limits.