I would suggest you don't cancel and wait, for a few reasons.
I don't know which card you are waiting for, but since November prices have risen and the X3 is now £800 the X4 is £830 and the X2 £750. In the early days Nvidia gave manufacturers a $50 subsidy which you will lose if you cancel now.
You are 43 in the queue, which believe me could be a whole lot worse if you had ordered a different card, you are highly unlikely to be able to get a different one either here or from somewhere else unless you buy from a scalper.
My advice is don't quite now, send Inno some Emails asking what they are playing at sending so little to the UK, and asking what they intend to do about the situation might Gee them up a little.
I've been doing exactly that, making comments on all their facebook posts etc!