What are somethings I should buy for my pre op diet?? And Also what are somethings I should pack in my hospital bag

depends on what kind of pre-op diet your surgeon requires - they're not all the same. I was allowed to have unlimited ultra-low-cal or no-cal uncaffeinated beverages (like Crystal Light, for example), unlimited sugar free popsicles and sugar free Jello, 4-5 protein shakes a day, and a limited amount of broth and tomato juice/V8 ( I think it was a cup of each per day)

I wouldn't take much to the hospital as you're not likely to need or use it. Your phone and phone charger for sure. And wear baggy clothes that are easy to put on to wear home (in fact, I wore the same thing to the hospital that I wore home). Otherwise, I ended up sleeping most of the time. They gave me things like soap, shampoo, a disposal toothbrush and paste (although I'd brought my own). I really didn't need much... They'll have you in one of those hospital gowns and non-skid socks, too - so you really don't even need anything to sleep in or slippers - unless you really want to bring them..

Don't buy too much as your tastes or whwt you cwn tolerate may change after surgery. Also the amount you need willbe drastically less for quite a while. Better to buy in small quantities until you figure out what works and doesn't work.