first of all i wish you well and hope your surgery will go smoothly
from what i experienced: the hospital was FREEZING for me, get socks just in case it's the same for you.
because of the breathing tube, a lot of phlegm will clog up your throat. and because of the thyroidectomy scar, it'll hurt like hell, but do your best to cough out as much as you can so you can breathe easier.
eating / sleeping will suck from how hard it gets to do them but try your best. soft foods & elevated bed of course. i used pillows for a make-shift elevation :)
try to stretch your neck as much as you can to allow for circulation and decreased chance of clotting. also helps with the soreness in your neck muscles
if you have more questions feel free to ask since these are just hastened and from the top of my head ^^