Gerhardt,
There should be an "official" discount in flying hours if you already possess a fixed-wing licence. There is much anecodal evidence to suggest that learning to fly a Schweizer takes fewer hours than an R22. So yes, knocking 10 hours orf may be feasible depending on your aptitude.
Secondly, I hope that being 40 (a-hem) is no bar to being a commercial pilot as that is what I am doing at the mo!
At the risk of now being flamed.... I decided to learn on the Schweizer (and will do my CPL on the same aircraft) because it ain't a Robinson 22. If you can fly a Schweizer, you can fly any other helicopter except, perhaps, an R22!! If you want to instruct and want to instruct on R22, then go for same. But if you are thinking of a commercial licence flying different types, then you should find the transition from S300 to, say, Jet Ranger much easier.
Thirdly, there are many things that one can learn that you won't find in the text books; these you will only get from a good instructor. Try also "Learning to Fly Helicopters" by Randall Padfield; I found it an immensely enjoyable read even before I had 3 hours!!
Good luck!
Cheers
Whirlygig