You don't need to take anything.
It is useful to have some breastfeeding bras. If your boobs aren't too big I would recommend the Primark ones as they are stretchy and cheap - once you've got home, got the hang of things and the post-birth boobs have settled down, get properly measured around 6 weeks postpartum and buy some nicer feeding bras (Hot Milk are lovely) if you want to. Or stick with the cheap ones but potentially in a better fitting size. Shops like H&M also make nursing tank tops which are great for under a normal top or sleeping in.
Have a think about boob access on any clothes you put in your hospital bag. Open at the top, stretchy enough to pull down or loose enough to pull up. You can layer so loose top to pull up, stretchy vest to pull down, if you don't want to expose your tummy.
You likely won't leak until your mature milk comes in which doesn't happen until day 3-5, you'll probably be home by then, so no need to bring breast pads.
If you use social media, follow all the breastfeeding experts you can find on there. It can just be handy to have a load of drip drip bits of useful advice and tips. There are some good BF support groups on FB as well (and sadly some insane ones...) A decent BF book is nice if you have the kindle app on your phone. It can help you troubleshoot. Google is not your friend with a newborn. I would recommend The Positive Breastfeeding Book or The Womanly Art of Breastfeeding. (I'm sure there are other good ones!)
If you want to, you can try to hand express some colostrum from 37 weeks into sterile syringes (1ml or 2ml syringes, medical grade or buy from pharmacy) which you should label with your surname and the date and freeze. You can take those into hospital just in case. But this is not necessary at all it's just something to do if you want to.
If you need formula, a pump, bottles etc they will provide it. You only need to bring your own if you're planning to bottle feed.
Nipple cream (Lansinoh) can be good but I found my midwife had little sample packs they were willing to give me all 3 times so I never actually needed to use the tube I bought.