Bus from Bath to Heathrow

Depends on which terminal.

And which airline you are flying will determine which terminal.

If you can give us more information people will be able to give you a better answer.

If looking for arrival gates, is id meeting someone. Of course, then question - domestic or international flight?

Sorry for not giving more detail. I am flying American Airlines and landing in terminal 3.

The bus station is between terminal 2 and 3, and some of the coach lines stop at more than one terminal in addition to stopping at the station. The central area will be OK for you getting to Terminal 3, but your coach bus line may offer more direct service and may drop you off at your terminal.

https://www.heathrow.com/airport-guide/getting-around-heathrow/airport-maps

https://www.heathrow.com/transport-and-directions/buses-and-coaches/coaches

Happy travels,
-Alison