I'm probably not the most qualified person on this thread, but it sounds like you've just got pre-exam nerves. Your instructors wouldn't say you're ready if you're not, they don't gain anything by it. It seems everyone who's got to this stage and have posted on this thread, have gone through exactly the same feelings of unpreparedness. Most of them surprise themselves by performing well on the day, but even if you do fluff up some parts of it, you can still get a partial pass, which gives you the opportunity to brush up on the bits you failed on and take the remainder.
If you're really feeling unready, then another option may be to ask one of your (many!) instructors to take you through a mock test, just so you can get a handle on what you need to do, and any sticking points you might have. If your instructors are anything like mine, they'll want you to pass.
Go on, you can do it. No, really, you can!
-J