That seems a bit expensive.
The 3G models are an extra $130 more than the wi-fi models in the US which if you add VAT and a little Apple Tax™ should be about £110.
Let's take the 64GB 3G. It's $829 in the US, which at an exchange rate of 1.5 (£553) plus 17.5% VAT is already £649. So add import tax, duty and a sprinkle of UK Apple tax and is £699 really that much of a stretch?
Whatever, the precise price-point, it's going to be the greater part of 700 quid, without a doubt.