I was rereading Prince Caspian and noticed that in the start of the story they're in
an empty, sleepy country station, and there was hardly anyone on the platform but themselves
and then they're magically pulled away to Narnia from there (and at the end, they end up back on the platform).
Is it possible Rowling was inspired by this to have wizards and witches head to Hogwarts from a railway platform?
Oddly enough, Rowling has cited The Chronicles of Narnia as an inspiration for her King's Cross entryway to the world of magic, but not the part you're thinking of!
I found myself thinking about the wardrobe route to Narnia when Harry is told he has to hurl himself at a barrier in Kings Cross Station - it dissolves and he's on platform Nine and Three-Quarters, and there's the train for Hogwarts.
Source: an interview she did for the Sydney Morning Herald in 2001.
She's also claimed, in a piece of "writing by J. K. Rowling" on Pottermore, that she chose King's Cross as the point of entry for getting to Hogwarts because of its personal significance to her:
King’s Cross, which is one of London’s main railway stations, has a very personal significance for me, because my parents met on a train to Scotland which departed from King’s Cross station. For this reason, and because it has such an evocative and symbolic name, and because it is actually the right station to leave from if you were heading to Caledonia, I never knew the slightest indecision about the location of the portal that would take Harry to Hogwarts, or the means of transport that would take him there.
(It's possible that both of these are true - she could have been inspired by her personal/family history to use King's Cross, and inspired by Narnia to have Harry hurl himself at a wall - but if we're to take them as conflicting pieces of evidence, I'd much rather rely on the earlier statement from an interview than the later one from Pottermore. I'm frankly doubtful that all of those pieces of "writing by J. K. Rowling" on Pottermore were really written by her, and even if so, she seems to be putting less care into her new additions to the Potterverse lore these days than she did back when she was writing the books. It's worth noting that she misremembered King's Cross when writing the platform scene.)
