I contacted my carrier and got this answer:
"If the Apple handset does not give you the option to select 3G this is an apple issue nothing to do with your giffgaff sim or 02. The best way to confirm this is a handset issue is to try the sim in another unlocked handset and trying to select 3G."
and yes, the same sim in my old phone has the options for 3G and 2G.
So this is the case of two groups each blaming the other. BUT its clear to me even if my carrier thinks its Apple and even if it's not then its Apples fault for lack of communication. I think this is a common problem with this new phone. I even heard Jim Cramer on CNBC complaining his wife's new phone does not support 3G.