I've got winter lettuce growing in a raised bed - you're a little late to sow now but you might be lucky, especially if you put up some sort of cloche http://igrowveg.com/how-to-guides/winter-vegetable-growing-guides/growing-winter-lettuce/
I also grow Swiss Chard sown in the autumn - I sow mine in September for harvesting throughout the winter - again you're a little late but you might get a crop if the soil is still warm enough for germination.
Also now is the time to sow Broad Beans Aquadulce Claudia, which will grow through the winter and give you an early crop next spring (May -ish)
Otherwise, if you wanted to grow brassicas for harvesting in the winter (cabbage, kale, brussels sprouts etc) you needed to really plan ahead and sow the seeds in the spring, grow them through the summer, plant them into their final positions in the early autumn. Or you could have bought some plants ready to plant out in the autumn - there might still be some in the garden centres - why not pop along and see if they've got any left ?
Otherwise a really good way for gardeners to pass the time in the winter is to settle down on the sofa with seed catalogues and a piece of paper (or computer) and draw up a plan of what you're going to grow next year, how much room each variety will take up, what you can plant in it's place when you've harvested it etc - that sort of planning can take up a lot of time.
Good luck with your gardening 
