Jersey is a small (although busy) airport and little to do. Being in St Helier is preferable by far. The BA lounge is a single room, with a tv and a full self service bar. There is no food, other than crisps and fruit. It is right next to the gate so a good place to have a drink before boarding. A couple of hours to kill …. no. You’ll be thoroughly board!
As Alexlondon sys it is small, reasonably comfortable, there is a TV and they do have muffins and some tray bake cakes. However you don’t say if you are transfering flights or if you are already going to be in the island itself.