Rene – As others have said, the GCB is separate from the AP. The AP is paid on the day you pick up your new car. The GCB comes to you a few days later. People often talk about their AP as the net figure after the GCB but this is false really as the two are completely separate and you get the GCB even if you leave the scheme!
I wouldn’t worry about getting the GCB if your car is tidy. Some folk have posted pictures on here of what looks like quite bad accident damage and certainly way in excess of ‘fair wear and tear’ and have still got their GCB!