It will be interesting to see how they handle the activation in the UK. In the states, you just walk into the Apple store or ATT store and buy the box and go home. That's it--in and out in a minute.
Once you get home you open up iTunes and there is an iPhone activation section where you go in, sign up for a plan and get a phone number. A few moments later (usually) your phone is active.
If the system is similar in the UK, I could imagine the Apple store being able to sell them. If there is some complicated in-store credit check, then it will probably be a carphonewarehouse kind of thing.
As for battery life--I should note the biggest draw on the thing is the wifi. If you leave wifi on, then you are going to be recharging quite a bit. The phone functions aren't that bad a draw, though supporting a big screen does take more power than your little tiny lcd in a basic phone.
