I'm so excited for you! This is a big step, but worth it.
I did not use any of the items I brought with me in the hospital, except the clothes to wear home. Hospital provides, basic care supplies and you will most likely just want to sleep or rest. Some suggested a notebook & pen for notes or journal, gas x strips, and ear plugs. The one thing I did not have when I got home was an old fashion night gown with no waist. My husband went & got 2 for me and that saved me! Couldn't handle anything around my waist for a week. Everyone is different though, but at least make sure you have comfy pants and tops for the first few weeks. Also I wouldn't leave the hospital without a prescription for nausea that dissolves under you tongue. Be prepared for an emotional ride the first 2 to 3 weeks, they feel like a roller-coaster, but it does get better as you heal and become more mobile. Make sure you have little 1 and 2 oz containers and cocktail size utensils at home. Also Lipton cup cream of chicken soup and chicken stock (not broth) to make it with, it adds protein and goes down well. It's a nice change from protein shakes also. You should read frequently asked questions in the pre-op forum section too. I've learned since my sleeve a month ago, that the only thing that has changed is the size of my stomach. It doesn't change food craving, choice of food we eat, what food triggers we have, our habits, or how much we exercise. We get full fast and that helps, will lose some weight no matter what, but all the rest we still have to work towards changing ourselves. We can do it though! I wish you all the best in your journey.