The trick is making your shopping total add up to £50 (as this is the minimum for using the code). And if you want to buy more items just make another account and use the code again on your £50 shopping. You can use the same name and address for delivery, just need different email accounts.
I found this very useful as they have some very good items on their sale. I bought some Lacoste trainers that used to be £70 and a diesel T shirt with £35 rrp and paid total of £42 +10.5% cash back from TCB with FREE delivery. Even managed to buy couple of jeans and etc in separate shopping and sold them off on ebay with £20-£40 profits.
£10 off code: WELC47JY http://www.topcashback.co.uk/zalando/
My first deal on here so I hope you find it useful.