buy Mums on Babies, there's a whole chapter on it
tbh, one woman's essential is another's poison. I actually dislike using cotton wool on my ds's bum because it leaves bits behind, I started with disposable wipes and now use fleece wipes.
If you have a car, you need a car seat.
Otherwise you need muslins a go-go and a few nappies of whatever sort you think you'll like. Don't sweat too much about this, or get advice from the nappy lady (search on here or Google I think).
you'll probably be given clothes but one pack of bodysuits (legless vests with poppers) and one pack of babygros isn't a bad idea, plus a hat and a blanket.
they need somewhere to sleep - in your bed is fine if that's what suits you - borrow a moses basket if you can.
I'd say a sling is essential. I'd also thoroughly recommend waiting to buy a pushchair until after the birth.
If you've got all those you'll be absolutely fine.