Just be clear and concise in your scenarios and empathetic towards the actor yet firm. Don't try and act, just be yourself and listen to the instructors.
The math's and English tests are extremely basic, and not designed to catch you out. Now the fitness test which everybody worries about, its 5.4 on the bleep test and slower you would be walking! Even with the most basic level of fitness you should be bale to breeze it, but if you are worried you have a week to prepare.