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

https://becketteulj000.cavandoragh.org/what-does-marketing-authorisation-mean-for-a-cannabis-medicine-in-the-uk

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. Despite this, cannabis remains a Class B drug for recreational use