I know. I think that occurs in every subject though. People walk in, believing that they're in for a 50 (or high 40s) and receive mucchhhh lower scores on their statement of marks. It's so much harder to do well than what's usually perceived, because although the exams often don't test an ability in the subject whatsoever, it's very easy to make careless mistakes under the pressure.
+1 Especially since we're talking about Further.
I remember when I was doing trial exams and I thought it was easy and had it pretty much sorted except for the odd question or two. But in exam 1, where every mark counts, I made too many silly mistakes and unfortunately, since exams hold the most weight in the calculation of the study score, I'm pretty screwed for a 40+.
EDIT: So my advice: Don't rush, don't panic and most important of all, don't be cocky.