Piggy, you can also use what is marked strong flour. US flour has more gluten due to more sun, strong flour has more gluten in it.
I wouldn't use it for delicate cakes, or for any UK recipe that calls for plain flour but it works fine for cookies and other US recipes.
I made 8 types of cookies at Christmas, about 6 dozen of each, and they all turned out fine. Well, except for the d@mn kiffles which always unfold themselves as they bake because my friend's mother won't give out her recipe. But they were still tasty.