If you’re not going to grow any winter veges, try growing a cover crop. A cover crop (green manure) will suppress weeds and put nutrients like nitrogen back into the soil.
Mustard is a good cover crop to grow (particularly in clay soil because it grows fast and it can be dug in before winter when the soil gets too hard), but not if you’re planting it where you’ve previously grown brassicas as it’s also a member of the brassica family and if there’s any club root in the soil it will promote it.
Another good cover crop is blue lupin, which isn’t a member of the brassica family. Before you sow the cover crop, dig the soil over and remove all weeds. Once sown, give the soil a water.
When the cover crop has matured (usually do this before it flowers), dig it into the soil. Do this around one month before planting at the latest and this will get the soil all ready for next season’s planting.