It appears the planes were very well protected in blast pens, distributed around the airfields rather than lined up, like Poland, France and later Russia. There was amazing organisation and planning that the Luftwaffe had never encountered - they did raid but there were a good few phantom airfields to mislead them too.
The German tactics during the battle of Britain was to try and destroy the RAF on the ground, various miss-calculations on squadron numbers and strength were made on both sides based on assumptions that each force had a similar number of pilots and aircraft as the other side. (iirc we had fewer squadrons but more aircraft and pilots per squadron making for more than the Germans thought but that's for another discussion)
as a result of these early attacks we switched to spreading aircraft out and explosive 'dumps' being well away from anything else in concrete bunkers.
The Germans decided that invading Britain wasn't going to happen in the near future (wanting air supremacy so that their troop ships can cross without risk of air attack) and so set about trying to disrupt UK industry by hitting the factories directly or disrupting the ability for people to get to work or move raw materials around. As we know, this was done by area bombing.
Due to factories often being nestled in amongst housing this had the result of houses being hit.
Not too sure (and not going to speculate) on if hitting workers houses was a byproduct of area bombing or deliberate, it is however known that the German high command believed it was only a short matter of time before the British people fled their towns and cities and rioted against the government.
