you will need to get liability insurance. This does not come cheap.
You would need to contact your local broker to find out more.
sit down and see if you really need it.
1. do you drive the customers cars
2. do you drive your car with the customer in it
3. mistakes & accidents do happen and it is only a matter of time before something happens. (hope not)
things you should also know. if you area mobil detailer and you are on your way to the customers home and you crash, if your insurance company finds this out, they may have your policy rerated to a commercial policy as you are using the car for business. depending on what your policy states as well they may be able to deny your claim as well.
The best thing to do is sit down with your local broker and go over everything, together you should be able to get a quote for liability insurance.
good luck
brian