Hi there, aah, well I'd tread very lightly on this one.

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The question on profit is one that needs to be decided by you. I.e you need to decided whether the amount charge for X jobs over a period of X hours is going to cover your overheads as well as wages etc if you have staff. In all honesty no one can tell you how much profit to make. You need to decide what you need to make for your company to operate and make profit in a competitive market place.
You have not given enough details for anyone to give you a reasonable answer. i.e how may hours does your cleaner work, who supplies materials, expenses etc., which are all needed to give you an answer worth considering.
As for the HMRC comment at the bottom you must pay the required contributions where staff have met their weekly or monthly thresholds.
I would suggest you seek advice on employment matters free from Acas or your local business advisor. This is because recent legislations surrounding payments to staff in real time etc., needs to be considered.
I hope this helps. Give them a call you will be given good information that will help you make the decisions you wish to make.
Good Luck