Brussels and onions/garlic yes. No to potatoes as not frost hardy. Broad beans can be sown late autumn or early pring (but check the seed packet since not all varieties are suitable for autumn/spring sowing).
Not too late to sow winter salads, again check the seed packets. Things like corn salad and many oriental salads should be ok. You may also still be ok with oriental spinach.
You can get horticultural fleece for a bit of frost protection.