I seem to remember if you list in business or first vs coach, London charges you more taxes to list in business and first.

I'll second Atlas if they have a flight that works. No stressing about getting a seat, they feed you well and its a guaranteed first class seat instead of a middle coach seat. When I did it they even offered me a bunk if I wanted it. Just search for their phone number and give them a call. Their online website listing in confusing since they ask for a flight number but you can't search their flights. I'd recommend jut calling them.