Hello there and welcome to BYC!
So glad you could join our community!
Some birds will lay all through out the winter, others will slow down and some can stop all together. So it depends on the breed. To keep them laying, they will need about 14 hours of daylight. So you would turn the light on about 2 hours before sun up and then turn it on again 2 hours after sun down, but NEVER leave it on 24/7. Always give them at least 8 full hours of complete darkness to keep the alive and healthy.
Turn off your heat lamp. Not only do these birds need to sleep, but they do not need heat unless your temps are in the minus zeros or more. Chickens come equipped with insulating feathers and can withstand the most brutal of temps if they have time to acclimate to the cold. There are members here in Alaska that keep their birds in uninsulated coops with no heat when temps are -40 degrees Fahrenheit. So if your over night low is going to be 30 or more degrees colder than your AVERAGE over night low, then you might turn on a lamp for them. You are not trying to heat the coop, but warm up their bubble of air around them. You can turn off the lamp when the temps return to your average over night low. And always permanently attach the heat lamp to the wall or ceiling and never rely on the clamp. They can fall and start a fire.
To keep birds warm in the coop at night, make sure to have adequate ventilation in your ceiling or eaves. about 1 square foot per bird. Venting on two opposing sides, one higher than the other. All the moisture from the pooping and the breathing needs to go somewhere and if it has no place to go, it falls back down on the birds as water or frost really chilling the birds. Keep the roost bar low to the floor so there is plenty of space between the ventilation and the birds. They will be sleeping in quiet air close to the floor as all the moisture rises and goes out the roof. Never close off all of your venting no matter how cold it gets. You can close off some of the lower venting during a windy night to control the movement of air, but always always always leave enough venting open to keep the birds dry which will keep them warm. You can also tack an old towel onto the roost bar to keep the feet warm. They lose heat through the feet. So warm feet mean warmer birds. And use a 2x4 with the 4 side up so they can tuck their feet under their breast feathers and keep them warm.
Good luck this winter with staying warm! Your birds will do fine in the cold. Let them out during the cold winter days if they wish. They will be so much more healthy if you let the acclimate to the cold and get out during the winter. Shovel the snowy paths for them if they wish to venture out into the snow.
Welcome to our flock!