Place of arrival when travelling to UK via connecting flights?

I'm travelling to Edinburgh for college tomorrow from India. While completing the mandatory passenger locator form, I am asked the following questions:

1. Where will you arrive in the UK?
2. What is your flight number?
3. What is the time of arrival?

Now it's not a direct flight. I'd be going from Kolkata (India) to Delhi (India); then Delhi to Heathrow; then finally Heathrow to Edinburgh. All of them are British Airways flights, booked under the same PNR but with different flight numbers. I am confused about what to put as answers to the above questions: for 1, should I write Heathrow, or Edinburgh? For 2, which flight do they want to know? Delhi to London or London to Edinburgh? And for 3, should I mention the time I arrive at London or the time I arrive at Edinburgh? Thanks in advance!