For the vegetable garden, there are plenty of spring cabbage and winter lettuce plants ready. If you have an empty cold glasshouse you could try a few spring cabbages in pots (use a soil-based compost). You will be cutting weeks ahead of the outdoor ones.
Mangetout are another worthwhile cold glass crop. If you can plant them in a tub or trough with some support, you can move them outside when you need the space in the spring. They are completely cold hardy but a bit of shelter from the drying wind helps enormously. We will sow a few trays if you want to try. They will crop in April and the cropping season is a lot longer than in the summer.
Watercress is another winter winner. It grows perfectly well in a pot and will not try and flower in the short days. It roots where the stems touch the soil so one pot from the herb bench planted in a 12” pot or bowl will keep you supplied all winter long.