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

https://kameronssuperbjournals.brightsora.com/posts/are-sativex-and-epidyolex-the-only-approved-cannabis-medicines-in-the-uk

In 2018, the UK amended the Misuse of Drugs Regulations 2001—not the 1971 Act—to allow certain cannabis-based medicines like Sativex and Epidyolex by prescription. These remain Class B drugs, prescribed only by specialist doctors under strict rules