Norweigen are the wrong airline and a 738 is the wrong aircraft for MAN-LGW sadly! Best options for the route are (IMHO) Flybe ~4 daily E195/175 or Easyjet 3/4 daily A319. Longer shots would be Virgin 3 daily A319 or BA re-instating the route at some point on the A319, which has a few less seats than the 734's and I would imagine, a slightly lower fuel burn however they would need around 4 daily flights including an overnighter @ MAN to keep the route attractive to those wishing to connect @ LGW and also business pax.