If I were you, I’d have a one-night bag with stuff for you and the baby, and a back-up bag your DH/DP can bring in from home if you have to stay longer. Saves a lot of painful conversations about exactly which nightie is the black one, etc.
Bear in mind you may not be mobile for a good 12 hours or so. I had my first CS late morning; they tried to get me to mobilise at midnight but I was exhausted and baby wouldn’t be put down so I asked to wait until first thing. My second one was mid afternoon and they said they wouldn’t get me up until the next morning. So you won’t be able to rummage through your own bag and may well need to direct a midwife to stuff.
With this in mind, what I found most useful was resealable plastic bags (Sainsbury’s do large food bags) which are ideal for separating things out in your bag/case. I had baby’s first outfit in one, for instance. I had another one with “bits” - hair bobble, deodorant, lip balm - all the little bits that would go awol in a case and which you can’t really be asking someone to keep finding for you. I just kept the bag on my hospital table and then I could just rummage myself.
Extra long phone charger and ask someone to plug it in and leave the wire accessible.
Some snacks in case you’re hungry - I had cereal bars and biscuits.
A water bottle you can open with one hand.
Toothbrush and shower stuff, and some wet wipes as an interim solution.
I’d probably only take a couple of nighties/pjs as I only got changed out of my hospital gown when I was up. Knickers and spares, and maybe three sets of vests/sleepsuits for baby.