What age/school year would you let your kids get the train by themselves?
To put into context 10 min walk to station (if that), 10 min train journey, 10 min walk other end (but likely to be picked up at station).
Context- pair of kids same age. Both have mobiles.
Train journey would be regular. They are familiar with where they're going at both ends.
(And usual caveat, I know it depends massively on the children in question, but this is about when you'd be okay with your own kids making this journey as a twosome).