Is there a reason you can't just cancel the order and buy from elsewhere?
It's £40.84 at Novatech, but it's
£40.74 with free delivery from Amazon, who list it as in stock, or
Pixmania have it at £39.73 (but charge £7+ for delivery).
Heck, even
PC World have it for £40.74 as their 'web exclusive' price.
Tip: if you have a local PC World, go down and see if they have one in stock. If they do, note that the shelf price is £65 or so. Amble over to the Mac section (because they tend to have internet access and not be locked). Go to PC World's website, do the 'reserve in store' option (which gets it for you at the web price, think there's a confirmation number you need to note down), and then take the keyboard over to the customer reservations desk and explain you've reserved this one and would like to buy it now thanks