Before you go to your Gastroenterologist appt. is it all right to eat or drink before you go.

It depends. What are you going for? Tests? If so, what kind? Why are you going to a gastro?

Depends on if they are going to perform any procedures. They will tell you in advance what to do or not to do if that is the case.

Usually the initial visit (which this sounds like) will determine what they want to do which they will schedule at that time and give you detailed instructions. When in doubt, always contact them to verify what you need to do.