That depends on which airline you are using. British Airways flies from Terminal 5.
There are various places you can fly to from Heathrow Terminal 3 such as Chicago USA, Amman, Oslo and Vancouver Canada. It is an International terminal that help you in your travel destination.
Delta uses Heathrow terminal T4.
Yes, there are three stations: Heathrow Terminal's 1,2 &3; Heathrow Terminal 4 and Heathrow Terminal 5. They are all situated on the Piccadilly Line.
Heathrow Terminal 5 is on M 25 motorway.
Terminal 5.
About 20 minutes.
There are about 30 miles from Whitechapel to Heathrow terminal 3.
Terminal 3
United Airlines uses Terminal 1 at Heathrow airport.
Lufthansa operates out of Terminal 2 at Heathrow Airport (IATA: LHR, ICAO: EGLL)
Pakistan International Airlines (PIA) uses Heathrow Terminal 3 for their flights to Karachi.
It is terminal 5 at London Heathrow Airport.