Do I need snow chains to go to Vaujany around Chrismas time?

On the continent you find ready mixed winter screen wash in 5 & 10 litre containers that operates down to -40 in most service stations so no problem there. Before you go empty your reservoir & refill it with with a neat or specfic concentration mix to at least -20.
We overlooked this last year & the journey was awful, once the wash lines were froze that was it.

I'd add a few audio books to the list. It's surprising how much faster the journey goes if you can listen to a couple of 2-hour books. Music CDs are OK but it can be hard to find something everyone likes and I find loud music distracting as a driver.