http://www.legislation.gov.uk/ukpga/2016/2/contents/enacted
https://en.wikipedia.org/wiki/Psychoactive_Substances_Act_20...
But also the UK has rapid powers to add a substance to the schedule in the Misuse of Drugs Act. Here's a recent list: https://www.gov.uk/government/publications/controlled-drugs-...
Here's schedule 2. I don't know how often this gets updated: http://www.legislation.gov.uk/ukpga/1971/38/schedule/2
> You can't legislate a state of mind,
You can legislate "intoxication", although the methods for doing so are pretty crude at the moment.