Last winter, I grew lettuce indoors under shoplights. Once the plants got going, we had all the lettuce the two of us could eat.
If it's warm
enough for you, it's warm enough for lettuce. Even if your house goes below freezing at night and the lettuce is limp in the morning, it will recover in time for dinner. I am not sure though that window light will be sufficient. I used two shoplights, each with one cool white and one warm white tube, and grew eight lettuce plants in an Earthbox. This winter, I'm going for two Earthboxes, so I can try some radishes and green onions.