I am going to be in arriving in London from abroad Tuesday morning and need to get to Camden from Victoria Station, I will then be leaving London Wednesday evening and so will need to travel from Camden Town back to Victoria Station again. So I will need a ticket to be able to travel on the underground or by bus for two days. My question is what is the most efficient way to pay for two day travel. Is it possible to get a two day travel pass? I assume paying for two separate one day passes is very expensive.
Get an Oyster Card or Use Your Contactless Payment Card
If you plan on travelling a total of two journeys in two days then you won't need a 2-day travel ticket (nor 2 day travel cards) as that would be to expressive, as well as overkill. The simplest option would be to get two one way tickets covering the zones you need. These will definitely be cheaper than daily tickets.
Having said this, your best bet is to get an oyster card, or even use your contactless payment card. Doing so you'll get the cheapest possible rates for your travels, and your maximum expenditure will be capped to the same value as that of a day travel card covering the zones you transited. Indeed, TfL agrees with me:
Only here for a short visit?
If you are only making one or two journeys when visiting London, pay as you go is the best option if you already have a contactless payment or Oyster card.
If you don't have one of these, you could consider getting an Oyster card which you can use whenever you visit London.
Alternatively, you could buy single tickets, a Day Travelcard or a One Day Bus & Tram Pass although these are all more expensive than using pay as you go.
You can buy an oyster card at many Tube stations in London, by asking at the manned ticket counter. For more information TfL has a page comparing oyster cards to travel cards, in terms of fares and usage.
How About Buses?
When it comes to buses however, note that recently TfL buses have become cash-free. This means that you can still purchase a single journey on a bus, but you'll have to use your payment card. You can of course use your contactless card to take advantage of the reduced oyster fares. The other obvious options is to purchase an oyster card and use that to pay for the bus.