Medical cannabis has been legal in the UK since 2018 for specific conditions....

https://doctiplus.net/arthritis-and-medical-cannabis-can-uk-patients-get-a-prescription/

Medical cannabis has been legal in the UK since 2018 for specific conditions. It isn’t a first-line treatment for arthritis; you’ll need a specialist assessment, usually through private clinics. Always chat with your GP to explore your options.