I doubt you'd find much in the way of condiments and such airside. You'd have to enter Jpn to find most of what you're looking for. Landside, T1's Lawson is small and limited although they do pack a lot of stuff in a tight space. With a 4-hr layover, you do have enough time for a quick trip to Narita town, should you change your mind and decide to enter Jpn. You could be stepping off the train at Keisei Narita or JR Narita 40-60min from gate, leaving you with ~1hr to shop at Narita. There's at least a couple of konbini's in the area, along with Matsumoto Kiyoshi. Don't know if there's a supermarket, though.