Unless you are carrying out a one off clean, it will be very difficult to price regular domestic work at a flat figure for the whole work. You will still be asked "How much is it per hour?".
Charging a fixed amount for regular domestic jobs is more popular in the US.
I have tried it some time ago but reverted back to the hourly rate quotations.
If you want to price different houses you will need to know how long it will take you or your cleaners to clean a 2 bed 1 bath, 2 bed 2 bath, 3 bed 2 bath houses etc. Then you calculate how much you pay your staff, include materials, equipment (if you provide these), insurance and your profit. The best idea is to survey each house so there are no surprises.
Good luck
Nick