You can still buy plug plants of different kinds of cabbage and kale in garden centres, plus some early purple sprouting broccoli for a spring crop. (make sure you can plant it somewhere that won't interfere with your crop rotation plans for next year, though.)
You can also sow Chard, spinach, Autumn Giant for winter carrots, French beans, Salad - lettuce or mixed salad seed, spring onions and beetroot
Good luck