Check each site’s licence on the UK Gambling Commission register, then read...

https://papa-wiki.win/index.php/What_makes_a_new_betting_website_%E2%80%98different%E2%80%99_besides_the_bonus%3F

Check each site’s licence on the UK Gambling Commission register, then read bonus terms: licensed operators face a 10x wagering cap. Treat headline offers sceptically, and check mobile usability, payment options and withdrawal times before signing up.