I did what you are asking about two years ago. As I understand it you still get 5 hours off the course, but, you'll like this bit, they bumped up the course from 40 to 45 hours. The extra 5 hours is instrument appreciation training in the event you enter cloud.
Now considering at every safety event I have been too they say never, ever fly into cloud in a small single engine helicopter on pain of certain death, its a bit like teaching you to do something really dumb, which of course you'll get blamed for in the accident report. Anyway I digress.
Whirlybird is right, you will not regret going for your PPL(H), I have not flown fixed wing since.
About doing it on or about the minimums, if you put in an instensive training period you can get close. I avoided the JAR route, just so only had to do 35 hours, I did it in 37 hours including the flight test.
Good luck.