Hi Dikid,
I didn't think I had fully cleared out before my last scope - I sat in the waiting room and in the exam room feeling like I really had to go, but the scope was perfectly clear with no sign of any left overs!
Try not to worry too much - if you can manage it just drink plenty of water up until the cut off time (I hate water, too - I just can't stomach it, so I put in the tiniest dash of squash just to sweeten it up a little!).
Just relax, think of the relaxed feeling from the sedation and look forward to going home!
Let us know how you get on