Related question -- how would (continental) Europe have evolved differently over the past five centuries absent English interventionism? Would this mean (earlier) political and/or economic unification; if so, when?
No. Honestly, I think that however much Britain attempted to forestall a European hegemon, their necessity in one not emerging is overrated. The thing to focus on is France, which had a huge population advantage over the rest of Europe from the Middle Ages, but didn't become a real unified political entity until about 1500. At the time, the Hapsburgs were able to stand them down for about two centuries, after which Prussia gradually became more important, eventually becoming the new preponderant power as a unified Germany. Russia also emerged around the same time, and they and France kept each other in check. All of this could have happened with or without British meddling, really.