I went in to the other day and bought a 13" white mac book with student discount.
Go into the apple store if you have one close by with your student card. All you need. All I took anyway just my university ID nothing else.
They will just scan your student card. Then ask one of the guys who can authorize the discount to do it and that's it. Take the apple care cover as well. Normally £190 or so. Its £44 I believe as a student, so worth taking for the 3 year peace of mind. Free iPod touch as well, or any iPod you want. Can only claim a maximum of £145 back though, so you still have to pay VAT basically.
The iPod you still have to fork out the £160+ up front. Then you send away for money back, either via mail in rebate or fill the form in on the net.
Think it came to around £700 for my Macbook, iPod touch and Apple care protection. Which is fairly cheap. Depending on the laptop you buy depends on the discount. You get a bit more off on the higher end laptops I believe. Least I was told I would get 17% off if I came back an bought a 17" MBP in a couple months.