Did you read the article? The legislation steadily increases the legal age limit so that kids don't get hooked on tobacco in the first place. No one will have to "quit cold turkey".

One of the biggest issues with the war on drugs is that it criminalizes the use of certain drugs. This doesn't do that.

As for your claim about a black market and a mafia:

we have already taken steps to reduce smoking rates. This includes providing 1 million smokers in England with free vape kits via our world-first ‘swap to stop’ scheme

They're still providing people with tobacco, just a less-deadly kind. Comparing that to the war on drugs is ridiculous. The point of the war on drugs isn't to get people to quit using dangerous drugs recreationally, every reasonable person wants that. The point of it is to control minorities and poor people. That's absolutely not what's happening here.

None of this is to defend Sunak btw, he's a broken clock that happens to be right in this instance.