I will post the image once it has rendered.. And the scene once it goes for planning application.
give it a a go and see if it helps.
Create a daylight system with inverse decay etc..
then go to lens shaders and place the night lume here...
drag the night lume to the material library as an instance and mess about with the settings.
Can get some really nice stuff
Bit of bodge but its the end image that counts i suppose