or will I just be able to put any sim (contract or pay as you go) and use it?
Added (1). Sorry, I should of clarified this first. When I say 'buy from the apple store' I mean online. So the phone would get shipped to my house, would I be able to use it with my current sim for example straight out the box.
Read more: If I buy an iPhone from the apple store, will I need to get it unlocked?