I'm a proponent of using authentic hops for finishing, especially in smaller beers like a bitter. You can use U.S. Goldings just fine for bittering, but if you want a good bitter, I think you should seek out the real English hops for your flavor/aroma additions.
That said, I did use U.S. Goldings as flavor additions in an English barleywine recently, and to be honest, I really don't get much hop flavor at all, nor do I feel I need to, since this beer is much more about malt complexity and smoothness of alcohol, as opposed to hop character, at least it is to me. So for that, I think it was fine. And it certainly did not ruin the beer at all! But it's all covered up with malt and alcohol.
For a bitter.... I'd try to find the real English stuff. But I guess I might use the U.S. version in a pinch (like, if I wanted to brew it TODAY and couldn't get it). I guess it all depends on how serious you are about making the most authentic possible example of the style.