I have done this a fair few times with apple and TNT, the process is pretty simple, I guess you called apple and told them you wanna return an item then they told you TNT will call you in a few days to arrange a pickup time.
Someone from TNT will call you soon and they will then ask you what time you would like them to pickup the apple product, as I remember they do collect items at night also, well atleast they do here in Sweden. If your prevented from being home at any time you can also arrange to personally deliver the package at their warehouse in the evening.
Either waybafter you've spoken to TNT on the phone they will email you some labels that you'll need to tape outside of your apple package.
there's no such thing as a restocking fee here in Europe, companies have to give you a full refund always, also apple doesn't charge you for the TNT pickup..good Service I guess.
Legally you have 14 days to return it counting from the day you contact apple, but as you've already called apple and their arranging for the package to get picked up there shouldn't be a problem. I've even returned products after 3 weeks and they didn't say anything about it.