The problem with an open fire, or indeed an enclosed wood burning stove, is that it draws the air it burns from the room its in and that air comes through a great variety of holes round the doors, window and up through the floor.
I would guess that the bungalow is full of holes and that it has a suspended wood floor, with large ventilators under?
Carefully designed to be well ventilated (freezing) to avoid condensation and wood rot.
I would also guess that when the fire is alight you are roasted on one side and frozen on the other, with the expensive warm air being burnt and sent up the chimney?
Rather than going to the expense of fitting a wood burner, that will not improve the ambience of the room, arrange things so that the holes are blocked, fitting hardboard and newspaper on the floor, to block the holes will help.
Fit a four inch pipe under the floor, starting at the outside and terminating near the fireplace, so that the fire burns fresh cold air from the outside.
This will eliminate the drafts and create a pleasant comfort zone.