What should i be preparing now to sow? have ordinary and red onions sets inside ready to dig in when weather better.Have potted up some herbs in green house at right temp and covered.Is there anything else i can do?

You could buy some seed potatoes and set them in egg boxes to chit (grow little shoots). Or shallots from sets. Soon you can sow leeks and a winter type of lettuce, and spinach.And tomatoes if you have heat. Buy Dr Hessayon's Veg and Herb Expert in paperback. It has good diagrams of sowing, planting and harvesting times that are easy and quick to read.