The problem seems to be that the phone providers in the UK are slacking with the nano sims. Tmobile say they wont even have theirs til October, DH asked in a store to confirm and the guy didnt even know what a nano sim was!
I got mine from 3 today but that means leaving Tesco mobile. Loads of other buyers are doing the same so they have a nano sim ready to activate next Friday. It's not as easy as micro sims, you have to cut and file a micro to make a nano and it's much easier to screw up