Tbh I wouldn't spend money on anything more than what primark or asda can offer to give birth in. I had a couple of Primark nighties and didn't have time to change - gave birth in the t shirt I went in wearing. The shirt style ones are great for breastfeeding and skin to skin.
Otherwise you want 3 categories - stuff for baby, stuff for you & stuff for partner.
Baby - 4 newborn vests & sleepsuits
4 0-3 vests and sleepsuits
A pack of nappies & bags.
Either cotton wool or wipes (I personally found wipes way easier)
2 hats
A blanket
Car seat (leave in the car until you need it)
Ready to go formula, just in case
A couple of muslins/swaddle blanket
You- a couple of nighties (prepare to throw them out, there is a lot of blood and nastiness involved)
A couple of packs of black big pants/disposable knickers
More maternity pads than you'll think you'll need, start with 2 packs.
Slippers
PJs (preferably with shorts, maternity wards are boiling)
A towel (dark colour if possible)
Snacks (I found the little concentrated bottles of squash were great)
A sports bottle/straws
Paracetamol
Face wipes/shower gel/make up/toothbrush & toothpaste/ lip balm/ hair bands
Nursing bras
nipple cream so important
Comfy clothes to leave hospital in
Phone charger (the external battery packs are also very useful)
Partner - spare change of clothes
Toothbrush & toothpaste
Phone charger
Pre made watsapp group of all important people you want to be informed when you go in.
It's also really appreciated to take something in for the midwives - a box of chocolates on a night shift goes down a treat.
There are loads of hospital bag lists on MN. Have a little read.