Grass on very gravelly area

Hi all, I'm looking to have grass on an area which was a drive way. What's left is a couple inches of fine gravel. When I take the pick axe to it there appears to be a few inches of the fine stuff before hitting bigger hardcore. Pictures attached. Any advice for preparing this area for sowing grass seed? I have an amount of topsoil to apply to the area but not sure if the grass would grow with what would be underneath the topsoil. Any advice greatly appreciated.

 

Grass needs a decent seedbed and soils structure if it is to make a nice lawn. If that is in the "too difficult" bracket you could go with Astoturf instead - that can go down straight onto your hardcore surface (with some sand in between)