Nichola is undoubtedly back, for those reading and wondering now:
first the walk is not that bad, but it's difficult to predict how anyone can do...and even the most fit have a bad day, twist an ankle, etc.
so:
https://www.caminodesantiago.me/community/resources/camino-del-norte-public-transportation.516/
(info compiled by Castilian, just made into a PDF by me
)
I think public transportation options on the Norte are phenomenal. One afternoon, looking for a place to stop, I found a beautiful hotel on the beach (literally steps to water), and was given a huge room with large balcony overlooking said water. For the next two steps I took the train to and from start/end points in order to come back and stay at that hotel. OK, I was also avoiding persistent pestering in the albergues
, but I would have done it anyway to listen to the waves at night).