The ME rating paper is pretty easy - I did it at PPL level i.e before I started to study ATPL theory.
You will have no problems at all with it. As long as you can do the basic PoF for an ME a/c you will be fine. The weight and balance is easy peasy, and the section about your a/c just know your basic aircraft manual.
Going back a long time now but I remember questions asked about the hydraulic reservoir, weight of the a/c etc
Best of Luck
Jinkster