Yep, the turkey in our freezer (locally raised, but purchased through the gourmet grocer we like) is 13-lbs and was the smallest whole turkey I could get. Anything smaller was breast only.I think probably around 90% of the turkeys sold over here are the same But there are a (growing) number of places online that will supply good quality birds, and even some of the supermarkets now stock better quality ones (though probably not as good as the artisan suppliers). We're very lucky that we can buy one from a local smallholding - you have to reserve one in September and you're never quite sure what size it'll be, but they are absolutely delicious.
We're always told that everything is bigger in the US ;-) obviously that's true for turkeys: TastyReuben mentioned about 20+ lb turkeys, and medtran49 mentioned that they get smaller turkeys weighing 11-13lbs ......I think the largest readily available in the UK are around 7kg (15lbs), I'm sure you can get bigger ones but they're not very common. We find a 4kg bird is plenty big enough to feed 6 of us, with plenty of leftovers.
Those Butterballs at the Kroger are like Frankenbirds. They're huge! The first year I made a turkey in the UK, I got my bird from the American commissary, so it was a Butterball or a Honeysuckle White, one of the national brands. I don't remember the size, but I brought it home, thawed it, got it all ready to go...and it wouldn't fit in my standard British cooker. Wasn't even close.
I should have cut it up and roasted it that way, but I ended up doing it on a charcoal grill. It took forever and was not very good. Actually, it was the worst turkey I've ever had.