In 2018, UK cannabis law changed through an update to the Misuse of Drugs...

https://kameronssuperbjournals.brightsora.com/posts/what-does-class-b-mean-for-cannabis-in-the-uk

In 2018, UK cannabis law changed through an update to the Misuse of Drugs Regulations 2001, not the Misuse of Drugs Act 1971. This allowed specialist doctors to prescribe cannabis-based medicines like Sativex and Epidyolex under Schedule 2