My husband and I will be traveling to London next month. We plan to be there for 6 days. Do we need to bring passport photos to get pay-as-you-go Oyster Cards?
No you do not need any id, money is the only thing you require.
Its optional if you want to register your details in case you lose it, for 6 days its not worth it.
For 6 days its probably worth getting a 7 day Travelcard that comes on an Oyster Card.
There is I believe a maximum daily charge on your oyster card of 4.5 pounds. After that you're traveling for free within London. It's easy to buy your card at Heathrow - follow signs to the underground. If you arrive late in the evening the charge into London from Heathrow on your card is that maximum 4.5 pounds (IF I remember correctly). Should you need to top off your card there are easy to use machines before the turnstiles at most, if not all, underground stations. Cash or credit card.
I just returned from London a few days ago. The previous posters have it right. The only thing I can add is to know which option you want. Maybe he was having a bad day but the clerk I was dealing with wasn't interested in explaining all the options. I went with the pay-as-you go card as I plan on returning often and the card doesn't expire.
Only problem with the PAYG Oyster Card is that you can't use it on the surface railways (not the London Underground) like the line out to Hampton Court.
You can use the paper Travelcards on these though.
Be sure to check out the Transport of London website http://www.tfl.gov.uk/ It is very helpful. The 7 day travel card may be a better deal over the PAYG depending on how much you will use the tubes/buses and where you are going to and coming from. A 7 day card is purchased based on what zones you will be using. Check out the tube maps (on the website) to see the different zones (Heathrow is in zone 6 and The City is in zone 1). Buy the card for the main zones you will be using and then you can "top up" for the occasionaly zones you might use. Just tell the people at the underground station where you buy your Oyster what part of town you will be staying in and where you plan to go and they get you all set up. They are usually very helpful, just explain your situation and ask for their advice. Have a great trip!