Interesting. JAA does not mandate a pre-solo exam at all. Whatever the school wants to impose is the discretion of the school. A lot of UK schools use the air law exam as a sort of pre-solo exam, but personally I like the FAA-style exam better: 18 or so questions on airframe, local airspace, emergencies and a few other things. You have to have all 18 right, but if you get one wrong, the instructor is allowed to explain the answer to you and sign you off anyway.
So this exam you've got to do, is it a school-imposed exam, or something the Swedish CAA imposes on top of the JAA requirements?
In any case, you will probably find that the exam is the exact same next time you have a go at it.