iPhone Need advice ASAP! Downgrading UK

I'm from the UK and have an A1429 model iPhone 5.
I'm currently running ios 7 beta, but need to downgrade back to ios6 as the phone is for sale now.

It says that my phone is GSM + CDMA on the apple website, does anyone have a link to the right IPSW file for me

I'm really at a loss as to which to install.
I believe it is the GSM 6.1.4 ipsw i need to install, but not sure.
thanks

BvizioN said:

Wouldn't iTune be able to automatically figure that for you? I would have thought so. I would say put the phone on DFU mode and then reinstall from iTunes.

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I wasn't sure if iTunes would allow me to restore to iOS 6, i'd read articles online that say you can only do it from restoring from a downloaded ispw?

If not, i can try it later

thanks