I'm sure pilots from all participating air forces shot enemy pilots either in chutes, in the water after they ditched, or on the ground after they belly landed. RAF pilots couldn't have been an exception. British pilots were desperately defending their homeland just like the Poles tried to do, and I'm sure were just about as aggressive about it. Most of the accounts I've heard the pilots excused this by saying the enemy pilot was good and they could be saving their countrymen from being shot down by the guy later.
As far as the early planes...I wish more people would feel that way about early models: maybe the early war and midwar arenas would be worth the server space if significant numbers of players wanted to fly spit 5 against 109E etc. As it is very few people fly in there and it's a little boring, and in fact finishing number one overall in early war isn't regarded as much of an accomplishment.