Can someone please explain to me what the best option would be ticket wise for occasional tube and bus trips for a 2 day trip to london. have looked at TFL and am completely baffled by oyster cards travelcards and photocards and the like...my DH and I would be travelling with them. I think we would prob walk quite a lot but might want to make 2-3 trips by public transport during visit. what would the cheapest and best option be for us? thanks