A heat lamp isn't necessary most of the time in most of the countries. If you give them a basking area with a light fixture (like a clamp lamp) using a 40 or 60 watt bulb. (Be sure to check your temps before putting it up). Night temps for them can be as low as 65, maybe 60, as long as they have a basking spot in the morning. Veileds have a tolerance for cooler temps. My daytime temps in my house are about 75. Their basking spot raises it to 85 in their spot. I have used a thermometer to measure this.