Its the section between Tertre Rouge and junction 23 that I was hoping to find somewhere.
There's no supermarket likely to be open when you arrive in that area. You might consider making a quick stop-off at Carrefour at Chartres. It's very close to the A11 autoroute. Just come off at junction 2 (N10 to Chartres), take the Chartres direction and it's next to the road at less than 1 mile. It closes at 9:30pm.