Prey tell what will the 20-30 million people (or whatever) do once the ban on ICE's comes into play? Please explain.
20-30 million...?!

There's only 68 million in the whole country! Of those, only 42 million even have a driving licence! And of those only about 35 million actually own a car...
So I think we can fairly safely say that it's not going to be 20-30 million people we're talking about here...
But yes, some will struggle to switch to an EV right now. That's why this is going to be quite a long haul. Let's assume that Labour manage to cling to their 2030 "vanity date" for ending new sales of pure ICEs. (Something doubt, but let's assume it anyway as a worst case).
So in 2030,
IF they want a new car at all, they're going to have to buy a hybrid. No probs. They can fill those with fuel like any ICE, if they're still desperate to give the oil companies their money.
Then in 2035, folk won't be able to buy new cars with any kind of petrol or diesel engine in them. Of course, even then, they won't have to buy a battery EV. They could buy a hydrogen car (lots of people keep telling us that hydrogen is the future, after all)...

No problems not being able to refuel your hydrogen car at home, because nobody will be able to do that, so it'll still just be like an ICE, having to drive to a special place to get your fuel....
But maybe even that's too big a leap and you need to get your "oil fix" for an ICE car. They live about 15 years on average, so you're not likely to see viable second hand ones disappearing until around 2050
Do you really feel that by then, we won't have suitable charging solutions available? Other countries (with far higher percentages of their populations living in flats an apartments seem to be managing!