Facebook’s promotional guidelines are quite clear – they don’t want you using their features as entry mechanics to competitions. Rewarding your fans with freebies is not necessarily a competition. However asking your fans to tag themselves by a specific date in order to receive a free voucher … I don’t know. What do you think? Is this a competition?
P.S. Not sure why step one is a search query instruction instead of “click here to go to our Facebook page” either.