I am going in for a Gummy smile surgery aka a gum lift and I just want to know what I will feel during surgery?

Nothing to worry about. If you are seeing a specialist, this is something they do all day long and know how to manage discomfort. In my experience, I do these procedures with sedation so no one feels anything or is even aware. They forget the appointment due to the effect of the drugs we use and they don't swell up as much due to anti-inflammatory medications and antibiotics we give them intravenous. It's the best way to have surgery and safest. If anyone in your area can give you sedation, you would love it! 

Being nervous about any type of dental procedure
is normal, but definitely inform your surgeon about your concerns. I use a
local anesthetic during the type of procedure you're describing so my patients
don't experience any pain or discomfort. You may feel some vibration or
pressure, but the area is fully numb. Once the anesthetic wears off, there is
typically some discomfort that is well managed with an over-the-counter pain
relief medication. Your dentist or his or her staff should be able to give you
this information over a brief phone call, so feel free to contact them. It will
help put your mind at ease. Good luck to you.

What you describe is also called a crown lengthening procedure.  Definitely let your surgeon know that you are quite anxious about receiving treatment.  They can take steps to help you feel less anxious prior to surgery and also ensure there is minimal if any discomfort before, during and after the procedure. 

There really is nothing to worry about. Most dentists will give you a local anesthetic at the beginning of your appointment to completely numb the area. If bone is removed you may feel some pressure or vibration when it is being removed. After the appointment the may be some mild discomfort but it can easily be managed with an over the counter pain reliever. If you are this nervous I would suggest visiting with your dentist about an anti anxiety medicine or sedation for the appointment.