Registering for GAMSTOP will prevent you from online logging into or setting up gambling accounts with businesses licensed in Great Britain if you are a UK resident. It is a free service. You can register for 6 months, 1 year or 5 years.
Find out more about multi operator self exclusion or watch this video https://vimeo.com/369796778
Their Terms and Conditions can be found here: https://www.gamstop.co.uk/contact-us