Getting iphone 5 on 12 month contract?

Basically, i'm thinking of getting a iphone 5, but when the new iphone comes out i wanna upgrade! There's still debates over the release date for the new iphone, from september to december!
with T-Mobile you get 15% off remaining payments! For example, if the new iphone came out in december- id have to pay 7 months of £53 but with the 15% off it would be- 45.05.

so i'm just trying to work out if its worth it or patience is better

If you really want the iPhone 6,
then wait…

But O2 refresh would the contract to look at
The network is 24 months 'like SIM only'
The phone is also 24 months, but separate 'like HP/loan' but still cheaper than buynig

when decemeber comes,
you take a new 24 months 'Phone only' contract for another 24 months (from then) but you keep your old 2 contracts (for another 16-17 months or so). You can always unlock the iPhone and sell it and put that money to one side to pay for the new phone/payments.

Or just go to an Apple shop directly and buy a 100% unlocked one
An unlocked one from Network shops is still locked to UK networks often (not 100% worldwiide unlocked)