You guys have come up with all the same things I found.
It's frustrating as hell, the groups you can see pretty easily, with variable level of detail, but the sectors are a nightmare.
They either cover them all really nicely, but name them after the base airfield instead of the official sector codes, or they only cover a single group.
This one is almost perfect
http://www.nationalarchives.gov.uk/wp-content/uploads/2019/03/AIR-41_16_1940-Battle-Britain.jpg but it doesn't cover enough area.
At the moment I am using QGIS to generate a map from a shape file, then adding detail by hand, but I am not a graphic artist.
This is what is known in the trade as "programmer art"
The area displayed in the map I generated is based on a single image of 11 group headquarters I have in a book I bought.
To give you some more detail, this image is to be used as a texture drawn on top of a table in the 3D scene that represents 11 group headquarters.
WAF officers will be animated plotting the incoming raids and you will be able to issue commands to all the squadrons in 11 group. Then jump into an aircraft as you wish.
So ....
Do you think I should start again?
Use QGIS to generate a map of the correct area then detail it to look like the period map and use the airfield names for each sector (which is not correct, but would make game play easier) ?
Do any of you guys want a go at this?