Can I use an ee contract sim in a new unlocked iPhone?

I'm just over a year into my contract so has just under a year to go but I want a new I have the hoc desire 610 at the moment but I want an iPhone 5s or 6. I believe that it is a Nano sim but I was wondering if it is possible to buy a used but unlocked iPhone and just use the SIM card still as I'm half way through my contract.

Yes, you can and I would like to recommend you the best security app that will be useful for you to secure all your media and that is Leo Privacy Guard.