Sowing for Autumn/Winter Harvests

I mainly eat stored food over winter: dried beans, potatoes, onions,tomatoes, garlic, soft fruit, pumpkin, squash, peas, apples hopefully till January. Then still from the garden/polytunnel: beetroot, carrot, cabbage, kale and leeks. 

The only thing I sow about now is Senshyu Yellow onion seeds. I used to grow sets but find seeds are far cheaper and the onions end up the same size. £1.19 + postage and there should be enough seeds for the next 2 years hopefully. I do tend to lose a good percentage of what I plant out but still end up with over 50 reasonable onions. I usually just leave the seedlings in a seed tray and they do look very vulnerable when I plant them out. This year I've put then in root trainers and hopefully they will be a bit sturdier and not have so much root disturbance when planted out.