Heathrow handles international and domestic passenger flights and is a major arrival point for a London visit. Its passenger terminals are numbered 2, 3, 4 and 5. Check the terminal for your specific flight before booking transport or meeting another traveller; the airport name alone is not enough to identify the correct arrival point.
Decide which rail service suits the journey
Heathrow Express serves London Paddington. The Elizabeth line provides a different stopping service, while the Piccadilly line is part of the Underground. Compare the actual destination, any interchange and the ticket conditions rather than assuming that all three services are interchangeable.
Follow signs for the service you have chosen and check the destination displayed on the train. Payment and ticket validity depend on the service. Engineering work can change the route, so consult Heathrow's current transport information and the relevant operator before travelling, particularly for an early departure or a return after a performance.
Moving between terminals
Use Heathrow's terminal-transfer instructions for the pair of terminals involved. Some transfers can use the pedestrian route between Terminals 2 and 3; journeys involving Terminals 4 or 5 use the appropriate rail connection. Free inter-terminal travel has its own ticket or payment instructions, which differ by service.
If you are connecting flights, follow the airport's flight-connections process rather than treating every change as a public transport journey. The airline and the airport's connection guidance determine whether you stay within the connection system or need to collect baggage and check in again. A separate ticket can change those arrangements.
Check-in and assistance
Use the airline's check-in and bag-drop deadlines for the flight you booked. Allow time for terminal navigation and security as well as the journey to the airport; an arrival at an airport railway station is not arrival at the gate.
Request assistance from the airline, travel agent or tour operator at least 48 hours before flying. Heathrow publishes separate guidance for departures, arrivals and connections, including support for non-visible disabilities. Explain your needs for the entire journey, including any terminal change, and confirm how assistance will continue to your onward transport.