So if you would like to pre order now then here are a few link to a few sites ( Trusted links )
I would rather wait until the Editions gets announced. But if you want to order soon please check out one of these links.
GAME - Halo 4 for £39.99 Free Delivery.
Play.com - Halo 4 for £44.99 Free Delivery.
Amazon.co.uk - Halo 4 for £37.95 Free Delivery.
GameStation - Halo 4 for £39.99 Free Delivery.
Hmv - Halo 4 for £37.99 Free Delivery.
Best buy - Halo 4 for $59.99
PS: Or you can pop into the shops on release day 