As usual BA's IT is woefully outdated.

https://www.gov.uk/foreign-travel-ad...y-requirements

No vaccination needed
No Air Suvidha needed
No declarations of any kind needed.

Just your passport and a visa if you need one.

I've been twice in the last couple of months and haven't seen a thermal scanner of any kind. And that 2% test thing, while technically current, they don't really do it as far as I know.

One thing to note - you need a filled in landing card at the immigration desk. BA used to hand them out on board just before landing - but they don't seem to be doing that anymore. Nor do they announce that one is needed.

Many people on my flight were caught out and showed up at the desk only to be turned away and told to come back with a landing card.

You can get one in the immigration hall just before you queue.
It's quite short and easy to fill in while queueing. Keep a pen handy.