Think you will have to let go of that one. An A320 won't work on NOC-BHX (nor would a 737-800), especially not under Aer Lingus' fare structure). You would also not get Aer Lingus introducing the route on anything but a stobart, it would be very rare for them to do so.
A jet aircraft is simply too much plane for that route. Look at SNN-MAN, it went from 3x daily flights on turboprops to a daily flight on a jet, despite the far lower fare structure.