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

https://www.tntmagazine.com/leisure-entertainment/leisure/why-is-cannabis-still-illegal-in-the-uk-the-history-behind-medical-cannabis-law/

In 2018, the UK updated the Misuse of Drugs Regulations 2001—not the 1971 Act—to allow specialist doctors to prescribe cannabis-based medicines like Sativex and Epidyolex under Schedule 2. Recreational cannabis remains a Class B drug