I'm working on a novel for teens in which two teens (one of them very unfit) go for about a 30 mile ride between two train stations. The key thing is that they have to go up and down 3 steep hills during the ride, and through a relatively remote valley. Ideally, this place would be within a couple of hours of London. Is there such a place? (or anything at all close?) What are the two train stations?

Many thanks,

Joe