Here's their small print:
Enter coupon code CYBERWEEKUK305 at checkout and receive 25% off your order. The maximum savings for this offer is £300. Sorry, but this offer is only valid in Pounds and cannot be applied to previous orders. You can only use this code once per account, and unfortunately you can't use this coupon in combination with other coupon codes. This great offers expires on 28 November 2011 at 11:59 PM, so don't miss out! While very unlikely, we do reserve the right to change or revoke this offer at anytime, and of course we cannot offer this coupon where it is against the law to do so.
So enter CYBERWEEKUK305 at checkout to receive 25% off your order, up to a maximum saving of £300.