As mentioned, Cite d'Europe is worth a visit. It's an outlet place with a large Carrefour hypermarket perfect for cheap wine etc. It's a few years since I went but there was also an Oakley outlet if you're after some new shades.
I had a camping holiday in France last September and the intention was to visit Cite d'Europe before catching the ferry back but we didn't leave enough time
We're going back this year but not getting a Calais ferry this time so won't be able to go, but intend on stocking up at another hypermarket