The 2010 11" MBA has been released. We're still waiting for the 2011 version to be released. Sorted.
And personally, if I were in the UK and had to put up with UK prices, I'd buy a 5 month old used 11" MBA for £300 less than a brand new one, or £100 less than a refurb. If I'm buying used rather than refurb (which comes with a new 1 year Apple warranty), there better be a damn good financial reason for it.
I don't know how much the current price in the UK is for a top spec 11" MBA, but I'd probably do the above.