If you are under glass or have a polytunnel you still have time to plant things up to overwinter. You will get a catch crop by the beginning of November that you can continue harvesting through out the winter. As long as they have some green left they will regenerate when the light turns in the middle of February and will keep you in fresh greens through the hungry gap into May when the new seasons plantings start to work.
These leafy vegetables really cross over between annual and the perennial approach to gardening beloved by permaculturalists. As long as you keep picking them they remain vegetative – sorrel does that too and its a really useful thing for intelligent gardening.