Most useful, vasaline for lips, as previously mentioned gas and air coupled with tropical temperatures in labour ward is very drying. Primark big knickers 2 sizes up, buy lots they are as cheap as chips, I ended up in these for a couple of weeks whilst using maternity pads.
Front opening nighties, I had to send dh out for more as couldn't wear pjs due to catheter. Slippers, phone and charger. If u can run to it a smart phone or iPad will save using expensive hospital internet if you stay any length of time, those hours after early morning feeds drag until visitors arrive, baby will sleep but you might struggle with all the noise and people checking up on you etc.
Things for baby, at least four baby grows and vests, small pack of nappies, nappy sacks, disposable bottles of formula if hospital don't provide it, just in case breast feeding doesn't work. Baby wipes, cotton wool just doesn't clean up newborn poo. I was glad of the extra pack in the bounty bag.
I didn't need towels and didn't eat the snacks I took or read the book, didn't have the concentration, a few magazines would be better. Took the little plastic water jug from my iron for rinising in the shower and nice shampoo and shower gel minatures really made me feel human. Don't forget toothbrush and toothpaste, you'll feel much better once you've cleaned your teeth.
If you stay in after dp goes home make sure he leaves you with water, tissues, wash bag, phone and baby changing bag within arms reach, I was bed bound for half a day and whilst staff were great you don't necessarily want to buzz them everytime you want a drink.
Have going home outfit in for both of you in car so dp can bring it and car seat when your ready. A spare pair of hands to carry everything you accumulate to car, or get dp to do several trips, I could only manage to carry a light bag and shuffle, what seemed like miles to car. A pillow to sit on, on way home would have been great.