Back garden is gravel over some sort of membrane but I would like a toddler friendly garden for the summertime. I've just moved in and the neighbours have said drainage is bad so grass dies. Some kind ladies in Chat yesterday suggested by removing the membrane but leaving the gravel & putting soil on top that would help with drainage so grass was an option after all (was previously considering fake grass).
All this gardening stuff is a complete mystery to me so if anybody could answer some questions I'd be ever so grateful 
Gravel area is approx 4mX6m, how much soil would I need? Does it need a thick layer or just a couple of cm?
Is a layer of gravel enough or would I need to put extra down for effective drainage?
If I chucked seed down would it be usable by the summer or should I get turf? Am in Scotland mind you so I appreciate summer may never come!