Well, the whole point of this test is that you cannot prepare for it in the way you might prepare for a normal exam. This means that the admissions tutors will get an idea of how you think when you haven't had chance to rehearse your answer.
But there is something you can do to give yourself some practice!
Ask your teacher (or a friend, parent or tutor) to give you a short poem or part of a piece of writing and give yourself 30 minutes to study it and write about it. You can get to grips with assessing something which has just been put in front of you for the first time.
You can also come up with an acronym for things which will be helpful for jogging your memory if your mind sometimes goes blank. Something like: F (form)
R (rhythm and pace)
O
S (style)
T (poetic techniques
These things will help you relax and think clearly during the ELAT but the answers you give will be your own. There is no way of knowing what will be on the test and it would be no fun for anyone if you did know. This test is designed so you can show off your own individual take on all sorts of poems and prose! Enjoy it!