charstar,
firstly i had my stage 1 a couple of weeks ago, its not exactly an interview. They are a set of tests testing your basic skills, if u read this forum then it will tell u what the tests are and it goes into detail of each test. One of the tests does involve the ATC paper part that you have received. All i will say is do your best to learn the paper and do not worry yourself too much if you can't remember it all all you can do is your best. The questions are multiple choice and are based on the document you are given.
Hope this helps
Loz x