I think there's a lot of geographical variation, I live in an area that would traditionally be considered very Tory-ish but it seems fairly common judging by the smell in public places. I have to admit my experience is probably biased by my social circle, but polling does suggest that staunch prohibitionists aren't nearly as common as our political climate would suggest.

This YouGov survey in 2019 has twice as many people supporting than opposing legalisation for example:

https://www.independent.co.uk/news/uk/home-news/cannabis-leg...