Great article on a variety of munitions used during the BoB including some data on penetration effectiveness at 200 yards against structure and light armour. Also mentions standard RAF convergence settings for the Spit and Hurricane at the beginning of the battle and later as operational experience was gained (e.g. convergence distances were reduced from 360 to 225 meters (393 yards to 246 yards).
http://www.quarry.nildram.co.uk/BoB.htm
The second article is a good comparative study of munitions effectiveness with some useful charts to help figure out your optimum ammo load.
http://www.quarry.nildram.co.uk/WW2guneffect.htm