IF it is a TURB that you are having, it is a "day surgery" procedure. I assume that they told you that you would be having anesthesia and that you could not drive home? If it is a TURB, the usual process is that they put you under, look into the bladder, and take small samples to send to the pathologist for review. It is only after the pathologist looks at the samples and sends his report to your urologist that you will know for sure what you are facing. This can take up to a week.
Most people (especially women) wake up and go home within an hour or so. Very occasionally, particularly with men, a urinary catheter is placed and has to be removed in the next day or so. Even more rarely, if the biopsy is extensive, they may keep a patient overnight.
I have had two of these. Neither caused any unpleasant after effects.
Good luck to you and let us know how it goes.
Sara Anne