I miss (and dream about sometimes) TCBY, and aways get a container of frozen yogurt larger than my skull when I fly through Atlanta airport.
Luckily my favorite fast food place has always been Subway, and to me English and Irish Subways taste the same as the American ones.
My husband likes McDonalds, and whenever we go, I usually get a milkshake or a pie only. Last time I got a chocolate milkshake and it was the most lack luster, vanilla-looking chocolate milkshake ever. That's the last time I get one of those!
To the OP, someone told me a while back they offer fresh, off the belt Krispy Kreme donuts at Gatwick Airport.