Build one up? Pretty easy to do, and how i got into riding fixed.
Or, if you want an Off the peg, Giant Bowery, Genisis Flyer, Specialized tricross and Kona paddy wagon are ones to look at.
Dont get a langster, please
Go for the one you like the look of more, the components one them are pretty much about the same, or nearly the same.
Try and get a deal with a few more sprockets and either another chain. But dont go for cheap crappy sprockets. Planet X/On One do good sprockets, that arent too expensive if your LBS doesnt have any to put in.
Where in the UK are you?