Calais-Ville is the main station in the centre of town; but, as Laura says, the Eurostars stop at Calais-Fréthun, which is a long way outside Calais, near the tunnel mouth. The docks are on the opposite side of the town 14Km from Calais-Fréthun.
See here for a map: http://www.openstreetmap.org/#map=13/50.9392/1.8094
Have you arranged your train booking from Calais to London? There are very few Eurostar trains to London which stop at Calais, only 3 per day (10:01, 14:01 and 21:01)
The full timetable is here: http://www.eurostar.com/sites/default/files/pdf/timetable/UK_timetable%281%29.pdf
Unless you are stopping somewhere in the Calais area, I would recommend dropping your car of at Lille Europe station, and catching your Eurostar there. If you look at the timetable there are many more trains stopping at Lille, approximately one every hour.
And Lille is a nice place to spend a few hours between dropping off the car and catching the Eurostar.