Tap the card you already have. Every Tube, bus, Elizabeth line, Overground and most suburban train gate takes a contactless bank card or phone. Tap in and out on rail; tap in only on buses. A zone 1 ride is £3.10 at peak and £3.00 off-peak; zones 1 to 2 are £3.60 and £3.10. The day caps at £8.90 for zones 1 and 2 and £16.30 for 1 to 6, and contactless also caps Monday to Sunday at £44.70 for zones 1 and 2. Use the same card at every gate. Almost everything you came for is in zones 1 and 2; Heathrow is zone 6.
Oyster is for the exceptions. The card costs £10 since September 2025 and the fee is not refunded. Buy one only if your bank charges foreign transaction fees. Children under 11 travel free with an adult; 11 to 15 year olds need an Oyster with the Young Visitor discount set at a station.
Heathrow and Gatwick. The Elizabeth line is 35 to 40 minutes from Heathrow to Paddington or Tottenham Court Road for £14.60 to £15.50 on contactless. The Piccadilly line is £5.90 and about an hour, inside the cap. Heathrow Express is 15 minutes to Paddington, £26 walk-up or from £10 booked ahead, outside the cap. From Gatwick, tap contactless on Thameslink to London Bridge, Farringdon or St Pancras in 30 to 45 minutes; Gatwick Express to Victoria costs roughly double.
Free museums. The British Museum (10 a.m. to 5 p.m., Friday to 8:30 p.m.), National Gallery (10 a.m. to 6 p.m., Friday to 9 p.m.), Tate Modern (10 a.m. to 6 p.m., Friday and Saturday to 9 p.m.), V&A (10 a.m. to 5:45 p.m., Friday to 10 p.m.), Natural History Museum and Science Museum are free and open every day. London does not do the Monday closure; the exception is Sir John Soane’s Museum, free but shut Monday and Tuesday.
Free but ticketed. The Science Museum requires a free timed ticket booked online. The Natural History Museum and British Museum ask you to book one and run a slower line for walk-ups on weekends and in school holidays. The National Gallery’s is optional and gives fast-track entry. Book them the night before; slots are rarely sold out, but the door scans them.
What charges. Tower of London £38, Westminster Abbey £32, Churchill War Rooms £34, and the view decks. The Tower and the Abbey sell timed slots; book the first one. The Abbey is for services only on Sunday.
On the day. Tap the same card everywhere and check the charge in your bank app that evening; a missed tap-out is charged as a maximum fare and can be disputed online. Save the museum slot in Waystop’s Documents, and check the late Friday openings in the list above before you plan an evening.