First off great looking plan.
My only two comments are these, a 12 platform station would not be served by a single mainline. If you look at prototype stations, anything above 5-6 platforms will have at least 3 lines but normally twin main lines. Adding this will make your station throat more complex but also more realistic.
Secondly moving from reception sidings to goods yard takes 4 movements. You need to consider a single head shunt to allow easy movement and shunting.
Oh and are you going to have a turntable?
As with both my points, take a look at the real thing. You have plenty of space just a little careful thought will add an extra dimension to your operation.
Don't forget to post some pics once you start building!!
