Jeff Watt, shame that your internal walls are not brick or stone.
I would cut the wall between the lounge and dining room, if possible. To stuff something allong those lines.
http://batchrocket.eu/en/applications#redbell
My latest desings are a bit more complicated than Peter's clean redbell.
I like to stick the firebox out of the bell, to fit a cast iron plate on top of it. For cooking. And make a door in the bell, to use as a oven. But i'm pretty much along the same lines.