Oyster Card

Oyster is a plastic smartcard you can use instead of paper tickets. You can put Travelcards, Bus & Tram season tickets and pay as you go credit on it. Oyster is the cheapest way to pay for single journeys on bus, Tube, tram, DLR, London Overground and most National Rail services in London.

Take all buss u want it, its amazing. xD Better that Portugal