Basically it is all down to how efficient the boiler is. The older boilers can cost a fortune to run, and if you're home is not very well insulated all the heat and money just goes out the window, walls and roof and it will have to work twice as hard just to maintain a comfortable temperature. You're Landlord would be responsible for the heatings maintenace and is by law required to have it checked out yearly and a valid certificte.
In winter my gas bill's are around �100 a quarter not a month. I have an energy efficient condensing boiler, K glass double glazing, wall insulation and 12" of loft insulation. The boiler once heated the house up only cliks on a couple of times a day to top up the temperature.