Yeah, ChAiNz, Jae is talking about something else. As of the last I heard, you need the product code, not the pre-order code to play after launch day. That code will be on the physical copy. So while you will be able to play from early access until launch date on the pre-order code as of December 20th you will be locked out until you get the product code.
Not that you would care with Skyrim setting on the computer.