Mally's suggestion is good to try, Lyn but when I moved and had surplus hardly used duvets and pillows I ended up having to give them to a dog rescue centre...none of the charity shops in town wanted them....x
I don't know of any charities which accept bedding to be offered for sale. (I doubt that any do).
However, as has been suggested above, there are charities which might accept bedding for use by the homeless or by animals. (I know that quite a few animal sanctuaries welcome bedding. My friend recently donated some old blankets, etc to one).
The problem with that is, TWR ....the bag may be stolen and if what's inside is no good to them the thieves will flytip or.......the charity shop volunteers will have to dispose of stuff left at their door which they can't sell ....or pay for it to be taken away....x
Homeless charities and night shelters will be most appreciative.
Animal shelters in my experience prefer fleeces as they are quick to wash and dry.
Leaving stuff outside a charity shop is foolhardy. Who wants to sort through a bag of sodden whatever before dumping it all in the bin, or as others have said it gets nicked and the redundant stuff abandoned.
Foolhardy or not the thought is there no matter how people think of it, hope you have a good news years eve Gness, have a few for me as I fly overhead lol xxx
Duvets aren't really of any use to a rough sleeper. Once they get wet...
That's why sleeping bags are preferred. Try a shelter if you have any near by.
Give it to a charity which helps homeless into homes and provides basics. E.g. I changed my useless electric hob for an induction one this year and gave my (now also useless) pans to The Hinge (Bridlington). They went to an elderly couple who, through no fault of their own, had found themselves homeless. The Hinge managed to find them a tiny flat they could afford, and my pans helped to furnish it for them. Good duvets would be welcome.