I'm guessing you wouldn't bother with us if it was something you could either fix yourself or if it wasn't all that bad.
Pitch a tent in the living room, it'll be easier to heat. If you normally sit on the floor then use a spare duvet or sleeping bag or whatever to insulate you from the cold floor. Students usually use old clothes waiting to be washed so they have this sorted. Keep the main room the smallest room and therefore easiest to heat. Big ass heavy curtains that reach to the floor also helps stop draughts from the windows, and if you fix one of the heavy curtains on a railing above the door it'll act as an effective draft excluder for the door. Make sure ALL doors are shut, ALL curtains have no gaps and you keep drinking hot drinks and all that other crap, hot beer may be required in some cases but very naughty. Buy a dog and use it's body heat to keep your feet warm, you may have to feed and take it for walks though. A fat girlfriend would be better, she'll keep you warmer than any dog ever should, she'll feed herself and maybe even you and even go to the bathroom herself. The hot air generated can also be utilised into a secondary heat element for the room. Buy an exercise bike, just in case you can't get a fatenough girlfriend and don't fancy dicking the dog. The excercise will generate body heat while watching TV, it'll help heat the room and heat you up to, although you'll burn through more food as a result. If all else fails rub two penguins together and set fire to the place.
Important: Buy a carbon monoxide detector alarm, if your heating is on constantly you just can't be too careful.