At phase 2, age doesn't really come into it. Well, age doesn't really come into it at any time for that matter. You've either got the skills and experience, or you don't. You'll find out on the day if you've really got what it takes.
I myself found the pilapt tests quite challenging and at the time I thought I had done badly but then got through. So just stay positive and keep that concentration up throughout the tests. You should be fine.
The only thing you can really prepare for is the maths questions. They're not too hard. As has been said. Just go over your long devision and long multiplication and it'll go alright.