I'm pretty sure if the person carries out a certain percentage of work for you and you tell them where to go, provide equipment, and what to do etc then self employed route is wrong and they must be employed. The only think I don't like about employing people is dealing with PAYE and HMRC, it's a pain and the latter are useless and providing revelant info.
Saying that though, the large cleaning companies like Maid to Clean and Kingsmaid all have people working for them on a self employed basis, it's bizzare.