Hi Karen - My advise would be DONT DO IT
We provided regular cleaning for 18 months and it was a nightmare. Its a service people want to pay peanuts for, they expect the earth, its difficult to get reliable & good cleaners. We get calls all the time about regular domestic cleaning and I would never go down this route again.
BUT if you want to do it you need to charge £15-£20 per hr to make it worth your while, as already said its not just the hourly rate you pay your cleaner and the difference is profit. take into consideration your time for organising it all, insurance, advertising, time for invoicing, processing wages, dealing with customer queries there's not much left after all that.
Sorry to seem harsh, its just my opinion from my experience.