I used to take Lydia on the train all the time to visit MIL (she lives just past wakefield)...in the days before I had a car lol.
Usually, at either end of the train, there are places for prams and wheelchairs, so you don't have to fold up the pram.
Actually, now that I think about it, I've never had to fold up a pram.
Mind you, those were Arriva trains, not the GNER ones, so it might be different if you're going on a big intercity train. But I'm sure they'll be pram spaces, because they've got to have wheelchair space.