France simply isn't capable of being the leader of a European confederacy whether economically or militarily unified. Even Germany isn't really the de-facto leader of the EU, they are basically a proxy for the US. I could see a UK that got its shit together being able to efficiently lead Europe but they don't really care enough plus I've noticed a curious trend among British people in that they don't really identify themselves as "European". There's almost an air of superiority present where they perceive themselves as better than and separate from the rest of the European nations. If you pay close enough attention you can even detect it among British far-right/white nationalist movements where they occasionally let the mask slip.