You'll struggle to get an I5 laptop for £400 or under,
however i found this: LENOVO G580 15.6" Laptop - Blue Deals | Pcworld
only £50 above budget and fitting what you want almost exactly. Lenovo are supposed to be really good at the moment :P (REVIEWS! :http://www.amazon.co.uk/product-reviews/B008HD8D8I
Although no graphics card
but integrated graphics on a laptop are normally enough for all your basic day to day computing.
unfortunatly you cant add a better GPU later, because laptop GPUs are normally built right into the motherboard.
And many of the people on these forums are from all around the world, obviously USA is a big place with lots of people so consequently there are many american people here, but there are some of us Brits XD