Thanks everyone.
I phoned PC world today and just by giving them my postcode and first line of address and confirming the serial number they linked the laptop to me and needed no receipt. They said they have logged it as a tech fault and not as damage and they would send a courier round to collect it. I decided just to take it into the store and it will be dispatched off for repair from there. They did try to charge me £30 for a data backup though but declined as I have it backed up anyway.
Considering what I have read about PC world customer service I was surprised at how easy going this was!
Am I in for some unpleasant surprises I wonder?