I like lists. So I'd make a list of eg what clothes/shoes/coats you need, choose them and pack them, bag up the rest and take to charity shop.
Another list of kitchen stuff, same process.
Furniture, choose what to keep and what to dispose of. If it's broken contact council to arrange bulky collection if you don't drive or book a slot to take to tip if you do drive. If you just don't like it and will replace in your new home with something else or you just don't need it any more, then advertise on Facebook marketplace and give away or sell cheaply to make sure it goes quickly. Or British Heart Foundation will collect, including working electricals and washing machine (they'll replace pipes or door rubbers etc if necessary).
Bathroom stuff, either do the list thing and donate the new and unused leftovers of products to a food bank, or box up the lot because it'll all get used eventually.
Go through bedding, get rid of stained ones or ones with broken fastenings into textile recycling. Box up the rest. Ditto raggedy towels that's past their best.
If you've too many books/CD/DVD pick out your favourite ones, leave the rest on your wall "free, help yourself" for passers by.