What mechanisms do you foresee for it to fail? If stores stop selling cigarettes, the UK will have no other choice but to stop smoking them. I wonder what will come to replace them though. People have a peculiar tendency of forming addictive habits.
Regarding question 2, personally, I am uncomfortable with the idea of a nanny state.
The rules are made by politicians.
All it takes to change the rules is to rotate politicians.
Or enough public dissent that the same politicians are forced to revert the rules.
This might play right into the hands of bootleggers and gangs but also into the Swedish / American nicotine pouch industry which is basically marketing straight at kids.
Also - vapes. Most folks don’t smoke cigarettes anymore. How does this control vaping?
It's like how everyone pat themselves on the back for banning child labor after the industrial revolution had rendered it obsolete outside a few niches that weren't economically important enough to put up a real fight.
Politicians "win" by pandering to voters and interests. So this is an obvious move since they can pander to all those people who grew up being told a cigarette takes a minute off your life while only pissing off some niche industry and a few smokers who are unwilling to vape.
I am a fairly regular weed smoker. I used to grow my own. I used to smoke tobacco. I can go weeks, months and even years without smoking weed. Kicking my nicotine habit took many, many, many tries and I didn't even enjoy it! They are not the same.