Again it would depend on what your girls are expected to do.........you really must get into the habit of visiting the clients before quoting.........it is difficult to quote on ANY job without a visit prior to starting.
Having said that, my experienced girls can do a regular clean of that type in 4 - 5 hours, providing an excellent clean and only 1 girl doing the job too.....at my hourly rate that would be £36 - £45.........
Are you saying you would put 2 cleaners in for 6 hours (3 man hours each) or 2 cleaners in for 12 hours (6 man hours each).
Whether or not you are in a wealthy area, I think £350.00 either way is a bit of an over-estimation.......if I charged those rates down here I wouldn't even have got off the ground, regardless of whether I was working in a wealthy part of the city or not! I charge the same hourly rate to ALL my customers, the difference in the cost to each comes in the length of time it takes to do the job. You would have some very upset customers on your hands if ever a time came when 2 of them knew each other and realised you were charging someone in a wealthy area more than someone not.
Then can you afford to lose the ones who can't afford you as you are charging too much in favour of the wealthier one! Course it's up to you, it's your business, but surely it would be better to find a happy medium.
It's all a learning curve Lisa and one we all have to learn for ourselves, and that's the hard bit!
Good luck anyway