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

https://rapid-wiki.win/index.php/Why_do_some_betting_sites_avoid_apps_and_stick_to_browser-only%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.