Can I Grow Lettuces During The Winter?

It is possible to grow lettuces during the winter but only if you have a greenhouse.  Theoretically it would be possible to grow them in pots and protect the pots with glass, but this is not as ideal as a greenhouse.
It is important to check out the type of seeds that you need for a winter crop.  There are some varieties such as Claret and Columbus which will grow well during the coldness and poor lighting conditions of winter.  Kelly's and Marmer are also good varieties and these have a crispier texture.  
If you sow the seeds now, growth is likely to be much slower than in summer, simply due to lack of heat and light, so you may be able to harvest them from January onwards but it would really only be with a heated greenhouse that you would be able to eat home grown lettuce on Christmas Day.