Having a few problems with diplomatic victory, need a bit of advice, please.

Hey, I'm playing as the French on a fractal map type. There's many city-states, and I'm planning on winning the vote through them. The problem is, I'm worried that England, which has turned into a runaway civ because they had an entire landmass to themselves, will win a Culture victory first. They've already completed 3/5 policy trees and we haven't reached the Atomic era yet. What can I do to help this? This is also GnK, by the way.

Also, I've declared war on Catherine, the weakest nation present, to gain favor with Japan. She also needs a smackdown, I'm getting tired of dealing with her. Unfortunately, I've been branded as a war-monger for this by everyone except Japan, who I wanted to stay good with, because they're pretty much the only people left who enjoy my presence. There's Elizabeth, Alexander (fuck that guy), Catherine and Oda. Should I just go ahead and eliminate Catherine, since I'm a war-monger anyway, and she's constantly denouncing me and bothering me and my city states with spies? I'm in a good position to do so.

TL;DR: Want Diplo victory, what do about England the runaway civ, have been branded a war-monger, do I eliminate Catherine since she won't vote for me anyway?