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

https://wiki-aero.win/index.php/Will_Medical_Cannabis_Make_Running_Feel_Weird_or_Unsafe%3F_A_Realistic_Guide_for_Runners

Medical cannabis has been legal in the UK since 2018 for specific conditions where other treatments haven’t provided relief. For runners exploring this path, access is provided through specialist private clinics following a clinical assessment