(Disclosure: This site contains product affiliate links. We may receive a commission if you make a purchase after clicking on one of these links. Read our affiliate disclosure for more info.)
Use the Promotional code XMASPLANET for 20% off your order at GamesPlanet.
It appears to work on everything except for pre-orders.
After the code Skyrim is only £18.75. This game uses Steamworks, so Steam activation is required.