you can stick your spuds now in for new pots at christmas dinner
i found that swiss chard stayed with me all through the winter (and is still going)
brasicas: sprouts, broccoli, cabages, caulis, etc
i just whack stuff in when there's some space and it seems to sort itself out with the timings.
of the above the spuds are the only ones that I've found suffer from frost damage, but once they are up and going closhes might be too small so you'd bebetter off with fleece.
of course, none of wht I've written should be taken as fact....I just wang it in the ground and hope.