Hi there,
Obviously I haven't been banded yet, so I'm not a complete expert, but first of all, I wanna say don't give up hope! My first few days of the liquid diet were utter-hell, but I'm now one week in and it's a lot better. Not just cause I'm in ketosis, but cause I'm used to it.
About what you said about your reasons for considering canceling.... You aren't gonna live your life with no choices. If you choose to have a glass of wine sometimes, it isn't going to kill you, it just might slow down your weight loss a little bit. Beer could be iffy cause of the carbonation, but really, I don't think that at the proper restriction, there is anything you'll have to avoid completely, just some things you'll have to enjoy in moderation, or knowing that you're choosing to enjoy that food or drink at the cost of a loss that week - which I think is a totally realistic and fine thing to choose sometimes.
I hope you start to find pre-op easier, and let us know if there's any way we can support you!
xox
angie