You may have spotted talk about shortages of fresh salad leaves this autumn and winter and if you want to to make sure you can continue to feed your salad habit now is the time to start sowing them.  Most of them with benefit from a bit of protection in a greenhouse or polytunnel, a mini-tunnel in the garden or even some horticultural fleece, but the hardiest ones like mustard should survive the winter without protection.  You can also grow most of them in a pot or a tray.    You can find some ideas of what to grow in this post on website of Real Seeds, a UK-based independent supplier of seed, but you can also get seed of most of these in garden centres or from other suppliers.