Based upon my experiences, I would make sure you have lots of clothes for you and the baby as you may be in longer than the usual 3 days. Or make sure you have a pile of clean stuff at home that your other half or family can bring in for you (they can also take your dirty clothes home to wash for you as well!)
Loose casual clothes are great for the daytimes. You may want to have a walk around the hospital once you are up and about. Being stuck on a ward 24 hours a day just made me feel more ill.
You may want to take your own pillow for home comfort, a camera to capture moments for when your other half is sent home (I hated these times), things to do ... books, magazines, kindle etc, puzzles, birth announcement cards to write etc
I was more prepared for my second section and took a bottle of made up squash (you need to drink lots after), some fruit, lots of mints (urgh hospital mouth) and some chocolate!
Oh nearly forgot .. a huge bath towel (you will want to have a shower or bath and may be accompanied by a midwife or health care assistant) and a dressing gown or long cardigan because they may make you walk down a very public corridor to the theatre in just a hospital gown with your backside on show to all the hospital (maybe that was just me?!)
I'm sure I will think of other things during the day!