There is still time to sow autumn and winter vegetables such as Chinese Cabbage, Kohl Rabi, Radish, Spinach, Spring Onions and Salad Leaves. They are all quick growing and you can begin cropping while they are very young.
One of the best salad mixes for overwintering is Provencale Salad Mix it has a good mix of winter hardy varieties to give you pickings over a long period.
As the nights turn cooler cover your crop with Fleece or a Cloche to encourage a longer cropping period well into the winter months.
Sow vegetables for over-wintering now such as Spring Cabbage, Kale and winter hardy lettuce such as Winter Density which has tender heads.