Thanks crewmeal, I tried my best.
SWBKCB, GrahamK, Dude~. Sorry about that, I messed up I was thinking £200 per passenger, so the calculations are probably a bit messed up after that, so then you'd have to add £200 per extra pax carried, but then with the new info you have given me regarding shortcuts etc, it's probably still 15-20 ish passengers to break even, no?
Dude~, as I said, I was sceptical about the figures I had, the website didn't seem the most professional but it had some numbers, so I used them.