Jack is pretty expensive and as I remember had a bar which did coffee etc. but no shop. There is however a shop around 5 minutes away (plus climber owned coffee shop) and camping here will get you a pass for your (hire?) car meaning it can be parked at the top of the local access road (it isn't a massive walk in without one but I'm not sure if you'd need to pay for daily parking in the town). If you get the chance I'd stock up on food at a large supermarket before you arrive (if possible).
I guess if you're going next week the others in the surrounding area will be open (isn't it going to be hot too?), they weren't when we visited so I can't help with that.
As I always say, ensure you go to the Luna hut and indulge in the local Pizzocheri, wine and coffee (their coffee is good). The owner is 'entertaining'. The pizza place is also good.
