Medical cannabis has been legal in the UK since 2018, though it is accessed...

https://angelowlnv711.yousher.com/can-i-travel-to-races-in-the-uk-with-prescribed-medical-cannabis

Medical cannabis has been legal in the UK since 2018, though it is accessed exclusively through specialist private clinics. To be eligible, patients must have a diagnosed condition and have already trialled conventional treatments without success