Nexus with SIM-only deal
I second BeerStirFry's point ...
It seems to me like it would be fine to buy it from the US store as it's compatible with any UK network. It's around £360 (inc shipping) for the phone. I notice that Vodafone UK are currently doing a SIM-only deal with 900 free minutes, unlimited texts and 500Mb mobile internet for just £20 per month. Slap that into the Nexus and you've got one of the cheapest smart phone deals around.... you can guarantee even Vodafone's own Nexus bundle won't come under £30 per month. Perhaps a good reason why the Nexus could soon outsell the iPhone.