I have a CPL/IR and almost 300 hours, and 150 P1. I trekked around almost every Parachute School in the south of England and had no joy. As has been said, there are a few single pistons around but most are turbine, often twin engined, and insurance stipulates at least 700 hours. The single pistons even wanted 400.
portsharbourflyer, I'd be interested to hear of anyone with only a 100 hour P1 requirement. I don't doubt there are a few places, but I haven't encountered them in my travels so far. Good luck all the same, you never know what opportunities there are.
h