Just to update for completeness sake, I have just gotten back from taking the exam and I PASSED! WHOOP! 
Have to say the exam was way harder than I expected, much more so than any of the mock exams I'd tried on the web. Also surprised that I had a fair number of questions on really small topics which I had never expected. And one big surprise was getting asked about vRam entilement in one of the questions!? I thought this went away when 5.1 came out and applied back to 5.0 so i didn't study any off that?
Oh well, a pass is a pass and I'll take it. Am so glad I can get 3-4hrs of my evenings back each night now