cotton wool
nappies (newborn size are up to 11lb, so get a couple of packs of those and maybe 1 of the next size up)
maternity pads
big knickers (to go over scar - I am still wearing mine 6 weeks after section, not the same pair, obviously!)
pram/pushchair/sling
muslins
lansinoh
breast pads
nursing bra
car seat
cot/moses basket/crib
bedding
v pillow is very handy, whether breast or formula feeding - esp with c-section (protects scar)
clothes wise I have tons of hand me down, but the only thing I have used in this hot weather is the sleepsuits, I haven't used a single vest, if I have gone out I put a jumper/cardigan over the top. At the hospital where I had ds they expected me to have a hat, vest and sleepsuit for him, when he was born. You might not need many newborn size clothes (ds just growing out of his at 6 weeks), so don't buy many.) 0-3 month clothes always looked vast on my dcs.
In hospital a Bounty lady will come round with a bag of freebies, which has a mini Sudocream, top to toe wash and baby oil. But they usually recommend you don't use anything for the first few weeks anyway.
I found a baby bath handy, because I couldn't bend over the big bath with my scar.
Make sure you have some comfy waisted trousers, because anything with zips or buttons digs into the scar.