Winter salad, early broad beans?

Pak choi and mizuna greens, radish, young beet.
Bear in mind though that even with all this protection, if the days are dull and cold with almost no sunshine, even in your frames the temperatures may dip well below freezing in extremely cold weather. Having gone to all this trouble it would make much more sense to bury some soil warming cables or a heated mat an inch or two underneath the frames, and that way you could grow many more things, from lettuce, to cress, to early seedlings. Such devices use very little electricity and yet make a huge difference in what you can do. Using this system to get lots of early plants next spring would be the most productive way. After all, broad beans will grow without protection any way.

Over wintering onions, garlic?