Hi, I formula fed my DS but some essentials are:
Muslin cloths- really good in the early days for wiping up bits of sick, dribble, etc. Also good if you're planning to use dummies because they get lost so easily but if you tie a dummy to each corner of the cloth it makes it a lot easier finding them!
Nappies/wipes/cotton wool/changing mat/changing bag- keep some nappies and wipes downstairs during the day and some more in your bedroom for the night.
Sleepsuits/long sleeve and short sleeve vests- I didnt really bother buying cute fancy little outfits for the first few months because they go through so many changes of clothes each day. I found sleepsuits more practical. Plus you're going to get lots of cute outfits as gifts so you don't need to buy any.
What are you planning to do for baby sleep wise? I used a Moses basket for the first 6 months but some people prefer a bassinet/crib type thing.
Stock up on the baby Calpol/Nurofen ready even thought they can't have it until 2-3 months just in case it slips your mind!
Head to toe wash, sudocrem, coconut oil, my DS had a lot of dry skin on his face when he was born so the coconut oil helped a lot.
Oh yeah before I forget mittens or sleepsuits with the inbuilt mittens is a good idea because there nails grow so quickly and they scratch themselves really easily.
I'm trying to think back to the early days lol.... but for breast feeding again other posters will be able to help you better but breast pads and nipple cream might be useful for you.
Lots of chocolate for yourself after the birth!
Wish you all the best!