I would use a cover crop, myself. Something like peas and oats, fava bean, or crimson clover. They will grow until hard freeze, choke out cool season weeds, and prevent erosion during the thaw, or winter rains. If they start to bloom, cut them down before the seeds ripen, and let them lie on the soil. Their roots will help with the soil texture and nutrient availability, and the whole plant becomes compost in place.

If you haven't dug it yet and there is quite an expanse of gound, then I would leave it a little longer and then rough dig it and let the frost and cold break it up which will also kill off overwintering slugs and other soil pests.

Could do with more details? What're you going to plant? How big is the area? Are you looking to protect it till Spring? Are you trying to suppress persistent weeds?
The 'lasagne method' might be what you're looking for

If you have the energy you can go with Jimmy's method but if you are a bit short of staying power like some of us these days you could use the plastic to cover the part you haven't managed to dig yet,not the dug part.. The part you have dug will be better either left to break down if it is clay and cloddy or otherwise just covered with your well rotted manure as a mulch and dug in come spring. Then weeds will germinate anyway so then quickly hoe them off while they are small.Or go with Tug's suggestion either, peas or clover would add nitrogen.
Or you could hire a cultivator, but not if you have couch grass as that would only spread it...

Thank you so much for your help.
I'll do the manure mulch and black poly the undug.
I'm posting another issue relating to a tree .... any help much appreciated.

Thank you.