Interesting, this topic always goes mental.
In practical terms, this means that many smokers will not be able to leave their houses.
Yes of course smoking is a choice, as is taking heroin, eating fatty food, drinking alcohol.
However for people who are addicted it's not as easy as snapping your fingers and stopping. It is an extremely addictive substance.
I don;t think that effectivle barring people who have not yet managed to give up from leaving their homes is on TBH.
Personally I think that the tobacco companies work very hard to get us addicted when we are very young and silly, they and the government make huge amounts of cash from smokers, to then say that in return they have to stay indoors does nit strike me as right.
If smoking is that offensive, even outdoors, then ban the sale of all tobacco products in the UK.
Plus as others have said, there are more concerning things. Fumes from vehicles which kill stacks of vulnerable people in London every year, for eg. Ban cars from cities, would make a huge difference to people's health, would mean thousands less deaths from crashes every year, and would make for much more clean and friendly environment.