The nearest International airport to Verbier is Geneva. Please arrange to arrive and depart at approximately 1400 hrs. I can then often combine minibus transfers, thereby keeping the costs as low as possible. Minibus transfer is the easiest and quickest way of getting to the resort, the journey time is under 2 hours and is a door to door service.  

Alternatively there is a regular train service from the airport to Martigny and then a half hour taxi ride up to Verbier. Children under 16 travel for free on Swiss railways.

If you decide to drive, the journey is easy and about 9 hours from Calais using the French autoroutes (toll payable).  I can easily arrange for you to spend the night before your arrival in the valley, thereby enabling you to have an extra day's skiing before settling into the chalet.