Medical cannabis has been legal in the UK via private clinics since 2018....

https://wiki-planet.win/index.php/Are_There_Follow-Up_Appointments_with_UK_Medical_Cannabis_Clinics%3F_A_Guide_for_Runners

Medical cannabis has been legal in the UK via private clinics since 2018. Eligibility depends on your specific condition and prior treatments. If you are a competitive athlete, note that WADA still prohibits THC during in-competition periods.