The Which guide to moving house says if you get a Mortgage Agreement in Principle (MAP) the credit search is registered on your file and the more searches that are registered the lower your credit rating becomes.
It says that if you shop around to see what rates lenders will give you that is not registered as a search.
Am I reading it right that you can do comparisons on websites like Moneysupermarket.com but until you get a written MAP it won't affect your credit rating?