That's much more reasonable - thanks! The Saturday flights you mention are direct from HEL to MAN on an Embraer - I'm guess that would only be 80 points, so I'll need to get another flight MAN to LON (Heathrow or similar). Happy to consider all reasonable suggestions.
Well, nothing really on Sat that's that cheap. Even during the week, say 9th June, it's £228 for a LHR-NCL same morning return (suppose you could reduce that price with Avios).
A lot of places in Europe don't seem to have any BA flights on a Saturday in June.