You can expect every aspect of your life to change. You will find a new normal. The old normal wasn't working so well, was it? Your new life will be so much better. Pre op is not easy, but it is only a small blip on the radar. Post op is not easy, but again, a small blip in the journey that will be the rest of your life. Preop is hard, also, because of the unknown. It is normal to be scared and anxious, but all of us on this side can tell you to jump into the pool - the water is fine and you won't drown. This is a good support group that will help you through.
Highly advise you to get on YouTube and start watching everything that has to do with weight loss surgery. You will get a ton of information that will make you better educated and realistic about what to expect in each step. Personally, I really liked Dr. Matthew Weiner. He does a good job of explaining the procedures, the diet stages (although it may differ from your own surgeon's), the recovery, different challenges in the process, and how to maintain.