We drive every year.
If you can go on a day other than Saturday, your trip will be shorter, but I know that may not be possible.
Take a packed breakfast and lunch, as the motorway services are very busy around lunchtimes, and try to time fuel stops for mid morning and mid afternoon, as well. There are loads of areas with a loo and a few picnic tables along the way, so there is no need to use services for comfort breaks. Do take your own tissues/loo roll and hand sanitiser, though.
You can get a badge for the tolls from the APRR website, which will speed up waiting times if there are queues at the tolls. (Liber-T, I think it's called)
Make sure you have all the stuff legally required by the French authorities. You can get information on line, and buy it all at halfords or the like. Particularly, remember snow chains. And make sure you know how to put them on the car. This has never happened to us, but apparently French police may stop you from ascending if it's snowing and you don't have chains.
We have done this quite a number of times, and it really is fine.