Frozen supermarket turkey should be safe for years, given the way they pump it full of brine under high pressure, to increase its weight (*), and reduce the risk of food poisoning for people who leave the cooked turkey lying around for days over Christmas.
Damn, reminds me, I haven't got round to ordering my goose yet. It's probably too late now.
(*) The supermarkets claim the brine treatment is designed to make it more juicy.