i have to say i always start my search with 0 ap and then work up to the level of gcb and any grant i may get.
as a wpms i do have that little bit extra to play with and i can get a grant of up to £640 towards an automatic once every 3 years. so potentially i can go up to £1200 ap without having to put in my own money so to speak.
the best i found were the suzuki ignis and seat arona as i need a higher seat but dont need a huge car. although the ignis auto seems to have disappeared recently.