Here's one code, let the fastest person win: 177KVX-86VBF-CF67-WDP-JG28S6D
When you use the code, don't forget to say so.
Re upgrading the account, the invite mail says: "If you upgrade* to a full Guild Wars 2 account, you will receive a bonus Booster Multipack in-game item packed with consumable boosters to give your character an edge! *Upgrade must occur by Nov 18th, 2012". It would seem you can upgrade it, then.