I only do significant digging to get perennial weeds out, particularly along the edge of my plot where they invade from the grass path which separates plots (I'm going to see if digging a shallow trench along the boundary helps). I've sown a green manure on some beds, the mild autumn meant the mustard grew and started flowering quickly so I cut it down. I have been collecting horse manure and spreading it on beds which don't have crops. It does seem to be working over the last few years. Despite not doing a major autumn/winter dig, and being on heavy clay, my soil has improved, it is less heavy and claggy and it is easier to get a fork in if I need to evict a dandelion or creeping buttercup. This autumn has been wet and dull so the soil is wet and the lack of sun means it isn't drying any time soon, so I think I'm best leaving it alone over winter, apart from continuing to spread horse manure. I'm lucky not to be infested with mares tail, the primary nuisance persistent weeds I have are bindweed, creeping buttercup, couch grass and dandelions.