Since 2018, medical cannabis has been available in the UK through regulated...

https://tiny-wiki.win/index.php/Is_Medical_Cannabis_for_Insomnia_Meant_to_be_Used_Long-Term_in_the_UK%3F

Since 2018, medical cannabis has been available in the UK through regulated specialist clinics. It is typically considered only after standard insomnia treatments have proven ineffective or unsuitable