Not sure if it helps in this specific instance but here's a site I buy RAM of all sorts from:
http://www.crucial.com
The UK specific one is:
http://www.crucial.com/uk/index.asp
Nb. They do other countries too, see the drop down-combo box in the top left of their pages.
I've always found them offering good prices, very prompt delivery and, perhaps more importantly, the correct memory for the job / machine.
Ps. I'm not associated or affiliated with them in any way - just trying to pass on a hopefully useful link.