I’m ideologically opposed to anything that prevents an adult from doing what they want to their own body.

A couple other comments seem to imply this a full-blown prohibition as well. To be clear, my interpretation is that this is not a total prohibition. From the article:

The government is set to introduce a historic new law to stop children who turn 14 this year or younger from ever legally being sold cigarettes in England, in a bid to create the first ‘smokefree generation’.

So IIUC, there is no possession or consumption offense, and anyone at any age can grow their own or import¹ it. They’re just making it inconvenient to acquire by controlling commerce. That inconvenience will certainly add to the cool factor of kids who become the resourceful hookup.

¹ I suppose they will be able to carry it into the country, but probably legit mail order shops will be controlled. Not sure.

On the other hand, a complete ban on smoking in public spaces could be helpful ? I’m not certain if it has been tried

IIRC, the smoking ban in restaurants and bars started in CA or NY, then swept around the world from there. Then NY supposedly banned smoking near outdoor bus stops or something. Not sure if that experiment spread.