The problem with lamps is they kill humidity. I use flexwatt (which is an under tank heater you can buy by the foot) plugged into thermostats. I take care of 26 snakes and there isn't a lightbulb to be found on any of their cages.

Matt at MGreptiles is the go-to guy for heat supplies (and most husbandry supplies really) http://www.mgreptiles.com/ I recommend a Johnson or Ranco thermostat.. or if you have the money, a helix or herpstat is great! Since your house is cool you may need two one foot pieces of flexwatt (the 11" kind is good) and two thermostats.. one set to keep half of the tank at 82-84 degrees, and the other set to 92-94. Nowhere in the cage should be below 80 degrees ever. A digital thermometer/hygrometer (you can get at walmart) is an indespensible aid