I'm sure you can find some UK sellers. I bought this universal charger recently, and while it isn't the cheapest it works nicely and it works with many batteries so shouldn't become redundant when I stop using my N900. Or there is this one whcih claims to be a UK seller. Or if you know someone who has a Nokia that uses the same battery (e.g. the 5800XM) then you can ask them nicely to charge your battery for you.