How much ?
-Like most things, it will depend where you are in the country. If you use an agency, you will pay more as well. I am in the Midlands and my wonderful cleaner charges £10ph and prefers to use her own cloth, sprays etc.
She does 2 hours per week, term time only (I had 3 teens at home when she started and it was a non-starter for her to come in the school holidays).
Your cleaner will be able to do a bit less to begin with and will speed up as she gets used to your house. Decide if you want her for 2 hours or for a specific set of jobs. Some people on MN get quite angsty if the cleaner leaves 15mins early, rather than thinking it is fine if she goes through everything a bit quicker.
I have kitchen, 2 bathrooms, hall, landings and 2 x stairs and 2 x living rooms done each week. There is usually a good 30 - 40 mins then when she does whatever I ask - might be bedrooms or even -very very occasionally-- ironing.
Some cleaners don't iron. Some people like beds to be changed.
What I take from cleaning threads on here is people all want different things, so communicate with her as she isn't a mind reader. Personally I don't want her to be shifting furniture and doing stuff I was never doing before she started, I want her to do what I would otherwise do, but some people are quite offended at a 'lighter touch' clean Neither is right or wrong, as long as she knows what you are after.
I LOVE coming into the house after she has been. It literally puts a huge smile on my face every week, 3 years in. Best money I spend.