I am a third year student at university. I am doing my dissertation on the effect that the change in tactics - from bombing airfields to cities - had on the outcome on the battle of Britain, discussing if that was the biggest factor in countering the odds into the RAF's favour. I am currently struggling to find many insightful primary sources around this subject. Would anybody be able to give me a point in the right direction? I am beginning to look at diary entries and the national archives, but would really appreciate some help. Apologies if this is the wrong sub. Thank you.
Here is a previous post by /u/Domini_canes discussing the situation of the RAF/Luftwaffe during the Battle of Britain. He/she draws upon Hastings and aircraft production numbers to show that the RAF always had higher aircraft production, even before the Blitz, and time was working in the favor of the UK.
Some important observations seem to be that:
While RAF airfields were under pressure, they had further airbases inland
The Luftwaffe was operating over much longer distances, which limited how many airbases they could actually strike if the RAF retreated inland
Hopefully this can give you some ideas in the right direction--unfortunately I don't know of any good sources outside of what was mentioned in the thread that I linked.