Buying Advance London Tube Tickets?

I've had this situation many times... 5 days + and it is cheapest to buy a weekly ticket, but less than 5 days (so in your case), your cheapest option is actually to buy a tube ticket for a whole day every single day. Day ticket is about 5.60 and a weekly is 25.50 or so. You can't actually buy these in advance, but every tube station has a ticket machine so you can do this relatively easily, it's quicker at smaller stations rather than main ones (Euston, Paddington, London Bridge, Victoria etc) because at the big ones there may be queues if it's peak travel time. Oyster cards are only cheaper/more convenient if you live in London, or are staying for weeks or months, because you pay 3 pounds to get the card and then either pay as you go and top up or you can put a weekly/monthl/yearly travel card on there. As I said, I've essed all the options and asked at ticket booths and the best option is simply a daily ticket purchased each day, one per person. Travel in central London is simply expensive :-s