Medical cannabis has been legally available in the UK since November 2018,...

https://wiki-coast.win/index.php/Is_Medical_Cannabis_a_First-Line_Treatment_in_the_UK%3F_Separating_Fact_from_Marketing

Medical cannabis has been legally available in the UK since November 2018, though it remains a specialist-only treatment. It is generally considered only after other licensed medications or therapies have failed to manage your condition