This depends on the types of tests your surgeon will be doing at your pre-op. Generally speaking, fasting is not necessary if blood work is not done. However, I would suggest asking your surgeon.
It really depends on what your specific plastic surgeon does for the pre-op appointment. In my practice, it isn't necessary because we aren't doing any blood work at that appointment. The blood work that I do send my patients elsewhere for does not require fasting. Make sure to check with your PS! Good luck with your upcoming surgery!
In general, if one is good physical condition, fasting for your preoperative appointment is not necessary. If your surgeon instructs you to specifically, then you should. This may be done if one is assessing blood sugars and medications for that. On the other hand, one should not have food or drink for a number of hours prior to your surgery. Often, instructions will prohibit food or drink after midnight the day before your surgery.