Welcome to BYC. Glad you decided to join our flock. If you're going to use a heater, a panel heater is a good way to go, but in my personal opinion, you don't need a heat lamp in Tennessee, especially with cold hardy breeds like Wyandottes. I've raised chickens where winter temperatures drop to 30 F below zero, and with a well ventilated (to keep moisture from building up), dry, and draft free coop, they did just fine. Feathers are wonderful insulators, and moisture is a much greater enemy than cold. Please feel free to ask any questions you may have. We are here to help in any way we can. Good luck with your Wyandottes.