paulc,
That is always a concern of mine when I travel. I have an expensive camera with a few lenses but have to carry a laptop for work.
I have generally found Air Canada and BA to be very good when taking it on as hand baggage, in fact the bag I use carries the all the gear and is below the UK guidelines on hand baggage sizing. These airlines are somewhat flexible on the weight too, as long as your not taking th p**s.
Not sure I would want to try it with the likes of FlyBe, Easy, etc though! There would be no way I would put that in the hold!