It's time to put in good use of your DSE giftcard :) I just got the Dicksmith catalogue in my letter box and I noticed some good deals. It says you get bonus $200 iTunes gift card for any Apple purchase of $1000 at Dicksmith. I couldn't find this anywhere on DSE website at all.
So it is great deal if you want to buy iPhone, iPad or Macbook or best one is Apple Watch (Apple Watch 2 maybe released in March though). It doesn't say in-store only and also doesn't have much detail on how to redeem them if you order online. I called the store and they said that you can get 2x $100 iTune gift card in store when you buy $1000 Apple products.
Many of Macbook is out of stock in store so I guess you will have to call DSE to confirm about this deal if you order online.
iTunes gift cards can't be used for hardware from my knowledge, only apps, movies, music etc…