In 2018, the UK amended the Misuse of Drugs Regulations 2001—not the 1971...

https://oscar-wiki.win/index.php/Why_Is_Change_to_UK_Cannabis_Law_So_Slow%3F

In 2018, the UK amended the Misuse of Drugs Regulations 2001—not the 1971 Act—to allow specialist doctors to prescribe cannabis-based medicines like Sativex and Epidyolex. Cannabis remains a Class B drug, with recreational use still illegal