can i get vat refund receipt after getting sudent discount

Nope. Not possible.

If you are purchasing a mac product in UK, you can either get a student discount or a VAT refund receipt. You can not get both. I am telling you this from my personal experience.

Anyways, a student discount is better than claiming your VAT. You get the discount on the spot whereas, there are certain procedures that need to be followed while claiming your VAT on the airport (lots of hassle).

Hope this helps...