clay soil

Hi my name is gavin im new to gardening what i wish to know is when i dug the grass off the top of my 8 square metre site there is about 5 inches of topsoil then some silty clay witch i have broken up with my shovel. Next i put composted manures and blood and bone pellets on it and dug that through. Next im going to put about six inches of topsoil and work the manures through that as well without disturbing the clay will this be enough coverage over the clay,i will be testing the soil for the ph levels because i really dont have a clue what i am doing any help would be great thanks.......