I was an *ahem* mature student too.
If you had researched well and memorized your info thats brilliant!
Thats half the battlle really, to gain marks in PP presentations we were told to have 3 or 4 (shortish) bullet pointed prompts of the main topics and expand on them.
It will differ depending on your course but ours didn't have to have any twirly bits (luckily!)
Just a small image in a corner to accompany the text.
I stuck to black text on cream or white large enough to be seen clearly from the back of the room.
5 slides is a good amount, tutors will appreciate quality of info over quantity.
Try to make your points correspond to the marking criteria.
Watch for silly mistakes (spelling errors, links work,) ask your tutor if you can do a dry run with them, like ben said the more you do it the more confident you get.
Have photocopies of the PP,3 slides per A4 sheet for the audience.
Your introduction and ending may be marked on too, always thank the listeners,you can also pick up extra marks of you suggest a Q&A.
Good luck.