Thanks everyone.
After much consideration of all your points, we're getting the train but not the Nozomi, to save on some costs.
With tolls, gas and a one way drop off fee the car did still work out cheaper than the train but not by enough to make it worthwhile risking the driving in the snow etc.
I love a self-drive holiday but I think in this case it's better not to.
Thank you so much
7 more sleeps!
