There is a Walmart right in Manchester. It's always a party in the parking lot! It's also a great place to buy last minute products. (The only time a year I will allow myself to shop there, if it's a dire item!) Lol.
Definitely fill up your tank before you leave the lot, in case you are in line long, or run your car while at camp, nd for the drive out.
ps- I see you are from Tampa. If you happen to have a spot in your car for my younger brother, he is super cool, and will only have a bag and a tent in the size of a small duffel bag. Let me know!!