We'll (2 adults and 2 kids) be in London for 3 days, arriving 9:20 am the first day. First, should we buy a travelcard for that day? I'm not sure what our plans will be, but we will probably go to Tower of London or walk around the city. The next two days, we will definitely be getting a travelcard. Is VisitBritain a good site to buy from and should we get our travelcards at London or order them? Sorry for all the questions, but thank you in advance!