Bluewolf,
Your living in the 1930's mate, not the 21st Century!
You also seem to be forgetting something called Trident.
UK is not a super power anymore. We may be the fourth richest economy on the planet but we are no where near the USA in terms of economic or military strength.
If China ever tries to become a major player on the world scene, and many political commentators note that if it did it would probably implode like the old Soviet Union did, then if it had any expansionist ambitions these would be matched and faced down by the combined strength of the free world led by the United States.
Don't forget, we (the UK) in no way could take on the Germans alone when they tried it twice in the last Century, that didn't stop us participating in a global campaign to stop them but no way could we ever have taken them on alone and won.
What makes you think China would be any different?
Also, what makes you think that China is going to be some militaristic expansionist state? They will have major challenges ahead of them, the most significant being how to hold together a huge monolithic state in the 21st Century world of instant global communication, fiscal dominance and human rights and individual expression.