I'm in Norwich and haven't been able to find any locally either. They have black currant instead... Which is ok, but just not the same as concord grape jelly! If I could find decent grapes I'd just make my own. At the moment we are just using homemade strawberry jam, honeysuckle flower jelly and banana jam. I'll definitely be bringing back some of my homemade jelly when I visit the states next as well as a few jars of bought grape jelly!
Also, have you tried nutella/chocolate spread with jelly/jam sandwiches? So much better tasting than peanut butter, but a lot less healthy as well!
My husband had never eaten nor even heard of a pb&j sandwich before I moved here either!