Some comments from myself, who has journeyed from non-smoker > disco smoker > smoker > heavy smoker > smoker + light vaper > heavy vaper, non-vaper and now limited use vaper.
I think this policy is there as a "pretend we're trying to protect the kids" policy, to con some adults into voting for them, the Nazi's used to do similar. The reality is of course that it doesn't protect anyone more than it's increasing risk elsewhere.
How many kids will it stop taking it up, how many adults? What is the cost of that/ the opposite reaction? There's always a cost/ opposite reaction, similar to what Newton used to say.
What is the public opinion from vapers who have used these to quit smoking? What was the route for them into quitting smoking? What about people still smoking? Seeing as we still have ~13% of adults who smoke, a millions who have quit (with ease) due to vaping, this is quite important.
If vaping is 5% of the damage of smoking (as per the governments own health review, among many others) then for every 20 you prevent starting vaping, then you only need 1 to start actual smoking and the risk is even. Will it work on a 20:1 ratio? Of course not, it will be lucky to be 55:1, in this area and then it gets even worse in other areas.
Reducing risk is great, but if the control measures increase risk elsewhere then it just becomes silly (more risk). The same applies to trying to control low risks, with poor controls, when there are easy options to control much higher risks, the latter makes more sense.
Same applies to the flavour options, if you limit this to actual cigarette tase, just nicotine (tasteless) or menthol, then you're going to drastically reduce the numbers moving from smoking to vaping to stopping altogether. This makes zero sense when cigarettes are still on sale, and the upping a year per year is far too slow in theory, and even slower in reality. Sure you can allow "fruit" flavours but ban "sweet" flavours but this will make absolutely zero difference of course, as they're practically identical and the exact same market.
So, lets look at the other consequences:
If you take this option away, for existing smokers, then they are more likely to continue with existing smoking, rather than moving over to something which is 1/20th of the risk. This is a far bigger problem, than new vapers (but not new smokers).
Not many moving from smoking to vaping is going from cigarettes to a £50 setup immediately, not unless they've had easy access to a smaller trial. Equally if the refillable option is £20 and the fags are £10 (no idea what they cost these days), then they will just buy the fags, or stay on them for longer, people don't change unless it's heavily incentivised and a disposable is what £3-£5?.
But, if you don't get people over from smoking> disposables, but from smoking> refillable, you're just opening the door to heavier use. A refillable is like 2ml of 10mg at 20 watts, but if you give them 2ml of 10mg, 80 Watts and another 8ml left in the bottle, then what do you think will happen? Correct, it goes from casual to permanent heavier use.
People completely ignoring disco smokers too, which is one of the main routes into smoking for adults, of any age. People get hammered, want something extra for one reason or another, or get peer pressured into it. Then either chose Vaping, Smoking actual cigarettes, Weed or even class A's. You're not going to change their personality, social scene, peer pressure etc, it's not controllable.
Vaping isn't really a route into smoking, it's a different path to nicotine and the result of that. Nobody vaping 6mg fruit juice is moving on to Malborough Reds (or lights), they've nothing to gain by doing this, so they don't. There's a lot to lose too, the tase and smell to most vapours who used to smoke, or who never smoked is sickening, so I doubt it's going to get many new takers, then obviously the cost and health risk is far higher, which everyone is well aware of.
Sure, we might end up with 20% vaping, rather than 12% smoking, but when the former is 1/20th of the risk, then the stat should be incomparable to most, or it should read 20%, which is 1% total risk or the other option is 12% which is 12% total risk.
Then there's also the actual benefits of nicotine, which people seem to casually ignore. It is calming, stress reducing and an appetite suppressant. The latter being quite important I think when we have a obesity crisis, especially in kids. It's fairly similar to caffeine, but probably much better for you than drinking 500ml of monster every day, or full fat coke which isn't much better.
Ban the actual UK legal sale of cigarettes first, for all ages via cost jacking, or rationing over the course of a year or two. Then if that manages to be possible, go after the vapers, if necessary (i.e if the problem is proven to be worse than other health issues).
To me the obesity crisis looks far worse, people say nothing if a kid is massively overweight (it's even frowned upon in social circles) and still allowed to buy chocolate bars and MacDonalds (or their parents are). Yet, if they use a weak vape once a week people see it as far worse, when it's not, from a risk and healthcare cost perspective. The main way it is wrong is that they are being able to do something illegal (which is 100% wrong), but that can controlled much, much better, with much heavier fines on shops and those giving them to kids etc.