Welcome to BYC. Glad you decided to join our flock. Where do you live? I don't personally recommend using a heat lamp as too many times they seem to cause a fire in some way or another. Feathers are wonderful insulators. I've raised chickens where winter temperatures dropped to 30 F below zero and my chickens were fine. Just make sure that their coop is well insulated with plenty of deep litter (pine shavings work well), draft free with good ventilation, and dry. Moisture is a greater threat to your chickens than cold. Please feel free to ask any other questions you may have. We are here to help in any way we can. What kind of chickens do you have?
You have the best answer already posted. Start planning for how to make sure they have unfrozen water available for the winter. Even in Georgia we had days last winter that freezing water was our primary problem.
X3 No heat lamps are needed for chickens. They have their own built in heaters and lots of warm feathers. They can acclimate to the most brutal of cold temps. If you find your birds are not laying through the winter, you might add some light to the coop. 14 hours of light will keep them laying. Never leave the light on 24 hours a day.