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It's a matter of what you and your body can tolerate. You're looking at about 10 hours out and 11 hours back. I've done Europe in Y and don't mind that much. Obviously J is better, but if it's out of my pocket, I wouldn't spend the extra $400 + miles. Then again, that's me. Others here whine if they have to do a transcon in Y.
If you have status with CO and could EUA a domestic portion, you may want to book IAH-EWR-LGW or IAH-IAD/JFK-LHR with the overwater portion on the Virgin codeshare.
Just some ideas.