Medical cannabis has been legal in the UK since 2018. You need a specialist...

https://echo-wiki.win/index.php/Can_Cancer_Patients_Get_Medical_Cannabis_for_Nausea_in_the_UK%3F

Medical cannabis has been legal in the UK since 2018. You need a specialist prescription, usually after other treatments fail. While available on the NHS, it’s rarely provided, so most patients use private clinics. It's a complex, regulated route.