By my experience (in most tutoring centres), in maths they'll just ask advanced level questions in your level and some questions from the year above you. For english, it will either be a comprehension (i.e. only short answer, long answer), or writing an essay or narrative in a given time.
Why 12 units? Most people do 6 subjects/10 units. I recommend dropping studies of religion and add physics and chem or even biology. Economics is basically redundant (legal studies for that matter) if you choose Business Studies over it, but if you want to, add it. Don't do history.