EKG and Fuggles go well together but I haven't brewed with Citra before. However, I have tasted plenty of beers with Citra. I honestly don't like Citra but I think that it would give fantastic depth of flavour if mixed with EKG and Fuggles. I'd keep it on the low side - perhaps no more than 20-30% of the total IBU contribution.
One thing I have learned though is that it's better to mix the hops throughout the additions to the kettle from boil through flavour on to aroma/flame out. In other words, it's better to add a mixture of x and y at 30 minutes rather than x at 30 minutes and y at 15 minutes. You get the picture.
I'd go for 50% EKG, 25% Fuggle and 25% Citra as a starting point. I've blended hops that you wouldn't think would go together (like German and American varieties) with great results. I don't see why EKG, Fuggles and Citra can't work.