Getting a Helicopter add-on is going to be easy and cheaper than if you were starting cold. I dont know of any school that has sought after graduates. I do know most Pilots have to beat on doors to get jobs.
One school that has been mentioned here many times is Heli-Adventures.
www.heli.com start there and see what happens. Most schools that I know of are out to sell you as much time as they can. They all seem to be driven by the dollar bill. Good Luck.