Depends what you want to achieve from regulation. I'd want to have it for over 21s (25s preferably, tbh) because of its effect on developing brains. I'd want it sold from well regulated licensed shops. I'd want to try and control the strains available to try and weed out (lolol) the most harmful strains, so would rather people were growing at home. Etc. There's also an argument around what forms it's available in - eg. smoking it is bloody stupid, really... there are far less harmful ways to consume it.
I'm happy to legalise most stuff... but I accept there's lots of potential harm so would rather regulate to reduce that as much as possible in a World where most stuff's legalised and relatively easily available.
They could just enforce a maximum thc content of around 10% or so (most modern strains are probably around 20% or higher)
10% is still kind of enough to get high but not stupidly potent so people can't be banging on about zombies or reefer madness.
Government gets some extra taxes
a lot of people gain employment
some of the dead high streets will have a bunch of headshops popping up or thc shops
fast food places sure get a boost from the munchies and so will other places that sell chocolate and sweets
in switzerland only CBD is legal, you can buy it in a lot of people these days, stoners don't like it so much since you never know if your dealer is mixing cbd with real illegal weed.
thc content must be under 1% I believe it is maybe 0.5% ? so no chance to get high.
seen CBD anged from 20-30% I don't think theres an actual limit cos theres no point really.
if switzerland can enforce a thc limit on cbd, theres no reason the UK couldn't do the same with a higher limit thats high enough to get stoned.
beats being full legal in most peoples eyes and could be the "brexit windfall" lol that pays for the nhs boost.. without raising normal taxes