No, I think that's a nice idea. I guess you would have to buy them a set of scales, because in the UK a lot of things are weighed (especially in baking), whereas in the US they are measured by volume.
I bought my Dad (in England) an American cookbook once and with it gave him a set of cup measures, so that he could measure out the ingredients.
Just thinking though, a cake baking book might be more tricky, not only because of the measuring aspect, but I think a lot of ingredients are a bit different. Like self raising flour. I don't think we have that here, but we have cake flour. (I'm not sure about all this though. I rarely bake here and I never baked in England.) My instinct would be a more general English cookbook, like Delia or something.