Hi,
I passed the test yestarday. I think if you are well prepared (meaning know the 3 chapters almost from words to word especially statistical data and dates) then you will not have probelm passing. I stated reading the book a week before the test, but I was studying real hard 2-3 days before the exam. What is easy about the test is the method of assesment (multiple choice questions), and the length of time available (45 minutes for 24 questions)
Be well prepared, especially look through the most difficult chapter ("How Britain is governed") and then you will pass for the first time and will not waist £34 and your time!
Good luck!