As a seed company, we tell people that when they pull something up, they need to put something in. The thing to do now is SOW BRASSICA's which are slow growing and will take you through the cold winters (cavolo nero, sprouts, cabbage, sprouting broccoli raab etc), but also to sow Spinach and lambs lettuces in Sep/Oct, Broad beans, peas and sugar snaps in Nov, garlic in Nov/Dec, radicchio and endive are great too as they resist cold. These are cold loving, you don't need to heat them, just keep snow off them, cloche, cold frame, cold greenhouse and there are others.