Sorry James, but you are going about this in totally the wrong way!! I made similar mistakes when I built my first part time round many years ago!! Put the ladders away, get yourself some good quality leaflets, deliver them to high end properties in good areas, and follow up by knocking the doors a few days later dressed in your company uniform.
Never ever offer one off cleans, many will ask for this anyway, but they are just a waste of time unless they are prepared to pay a very large premium for the service ie at least double the normal price, probably more! even then its not really worth it. I normally offer 1 or 2 monthly, if its a nice big house I will go to 3 monthly. And finally set yourself a decent minimum price! £8 is ridiculous!! Please don't take this the wrong way, I'm just trying to help.