I'm neck deep in trying to navigate my way around London in 2 weeks time! I'm travelling with my DH and 3 kids, 13, 11 and 9. As far as I can see, 9 year old travels free, and 13 and 11 half adult price on tube. However to get the half price travel everything I'm looking at seems to suggest we need to buy an oyster at £10.50 each. This is crazy for a 2 day trip! Can we not just buy the kids tickets at the station? Or do we just suck up paying adult price as I think it will be cheaper than buying oyster cards?