Earlier quoted context omitted.
That seems bizarre — you’re much more likely to be able to get it privately in India or Thailand or any other country that has good healthcare for the rich and few qualms about allowing people to buy in private stock. Much easier to pay $500 to a private clinic in Mumbai than fly to the West and hope that you can convince the state to provide it
The state will not provide it to non-residents. As soon as you arrive in the UK, immigration stamps "no recourse to public funds" in black all-caps into your passport as a friendly reminder.
However, in general, acute healthcare in free in the UK and does not even require ID. I don't know if that's how it's "meant" to be, but that's how it is; if you're on vacation in the UK and something bad happens, you can just turn up at the nearest hospital and it will get sorted out, no bill no fuss.