You do not need to book anything,
Just drive to a railway station, park your car, buy a ticket and go. There is the Mont Blanc Express from Martigny, or you can go from Aigle to Les Diablerets… A bit further there is Montreux - Rocher de Naye etc…
But what prompted you to go to Nendaz in November? There is nothing going on there this week. All you will do is spend a lot of time driving to and from the place…