Well, the main problem here is finding someone who doesn't already have the game, the finding of the code should be very easy :)
In all seriousness though, there should be two codes in the email (both clickable)... You are talking about the TW2/Gamers gift for stamp collecting, right?
Yes, that's the one, I don't want to click the link and commit myself to another version of it, or does clicking the link get you the code that you can give to someone else?
If you already own the game you will not receive it a second time, so you can savely click in any case :)
You should be redirected to the redeem page, where you'll have to confirm that you want to redeem (or, if you own the game already, it will tell you just that). So you can grab the code from there if you want.
What I find strange is that the code wasn't visible in the email you received? I just copy-pasted it from right there.
Hope all goes well, if the key "gets lost", it's not like there's a shortage ;)