Dig over as much of the soil as you can; clearing any debris
Fix and secure anything required ready for the winter months
If mild enough, plant out over wintering veg and dont forget protection against frosts and cold weather
Clear old and unwanted summer crops
Plant new fruit trees
Sow indoors/under glass:
There is not so much to sow in the greenhouse now but some can be transported outside to over winter. You may want a last go at peas that can be transported out later on.