I think an Empire would be better than a union.
An Empire of English speaking languages.
America(Co-leader), Canada(w/o Quebec), UK(Co-Leader), Belize, Australia, New Zealand, Guyana, and South Africa. With India as a protectorate.
The suggestion that all would submit to the US and UK as co-leaders tells me that you really don't understand the general sentiments of Canadians, Aussies, Kiwis etc.