I can't afford to feed 18 hens for 6 months with organic feed and get few or no eggs. At $80/mo. this is pretty pricey. I sell eggs and pretty much the hens pay for themselves.
So I do use lights, starting in August when the light gets below the 14 hr threshold. The lights go on around 3AM and off around 6PM. (It's dark enough in the coop that they are affected w/o the light being on.)
My hens aren't pets and will go to Freezer Camp at 18 months or perhaps as late as 19.5 months if they lay really well. That's when the new flock should be starting to lay well. If I've culled well, then none of them will have started molting at this point. If a hen hatched in mid spring starts to molt in the following summer, it's an idicator that she is probably not a good layer. Good layers will not molt until the fall.
We don't heat the coop per se, but do use heat lamps set on a Thermo-Cube to keep the water open. This is really important in the winter if they are laying. They need access to water when the light is on so they can digest the feed they eat. They don't get let out of the coop until 7:30 - 8AM when it's full light. If they can not eat as well as they need, they will not lay as well as they can.
If you plan to use a light, then you need to plan to make sure they have all the nutrition they need to lay well. They do not have the resources to lay and keep warm in the winter without good nutrition. Most of the breeds available today were bred to lay well on the commercial feed and if that is supplemented in winter, they should thrive vs survive.
I've often wondered what chickens closer to the equator do in "winter"? They get light year round naturally...granted maybe only 12 - 13 hrs....