The keyboard will also be different, no '£' key and some keys such as @ and " will be swapped round which can be a pain. I had a US laptop for several years and its fine if its the only machine you use, but a pain if you switch between that and a UK keyboard.
For delivery from HP sounds like you'd have to know someone who lives in or visits the States, unless there is a retailer who will ship to the UK, but then you could get stung by Customs!
I too have a new Dell laptop, got it last month and its great.