However in brief the following are the easiest approaches:

From Calais: Take the A26 Autoroute direction Reims, then Troyes, then Dijon and to Lyon. When you approach Lyon, follow signs to Grenoble.

From Grenoble: When you reach Grenoble stay on the by-pass heading South and exit at Sortie 8, direction Briançon. Drive through Vizille, and keep following directions to “Stations Oisans” and Briançon. Eventually you will pass through the town of Bourg d’Oisans. Continue towards Briançon until you reach Ferney d’Oisans. Turn left here and follow the road up towards Auris en Oisans. 3km before you get to the ski station you will see a turning right to the village of Les Cours. Further directions will be sent upon confirmation of booking.

Eurotunnel
From Folkstone it is 35 minutes to Calais and the French motorway system. Bookings can be made via Eurotunnel’s website. With the hassle of transport to and from airports, car parking, security and waiting, we have found Eurotunnel to be one of the quickest ways from the South of England to Grenoble.
http://www.eurotunnel.com

And Car Rental
https://www.europcar.com
http://www.hertz.co.uk