For my upcoming trip with 13 year old daughter, I am taking at least two trains: Watford Junction to the bus to Harry Potter; and Moreton in Marsh, Cotswold Tour. So now the questions is, which is the best purchase option? I see on the National Rail site, I can target those journeys round trip and pre-purchase the tickets, but is that the best option? I did purchase a hop-on-hop-off bus ticket for us which I think will be super fun for a 13 year old. Please advise. I am driving myself crazy.