To be perfectly honest, I wouldn't want one in my house.  Not without proper ventilation and a flue. I keep thinking of my (late) next door neighbours, who had double glazing put in but kept their open gas fires.  You could smell the fumes in the house, and they both died within a year.  OK, they were in their late eighties but I don't think the fumes helped.

Have you considered a convector heater with a thermostat and maybe a timer for the hour or so you need heat in the mornings? EDF have just notified me of their new prices - 14.5p per Kw Hr - so for example, a 2kw convector heater run full blast for an hour would cost 29p.  You can get them for £25-£40 , £35 average. The calor gas heaters seem to start at £64.