the top part nearest the house i have to smooth it out which will take a while so that it is 2 inches below the paths and then put down weedproof membrane and then these grid squares which all link together and you then put 10mm gravel down so it forms a firm base. you wont be able to see the plastic and it will support a wheelchair/walker etc. plus give a firm base for raised beds etc. eventually i will do the same to the grass to the left of the central path and put up a shed and greenhouse. the side i am currently working on will still slope away from the house a bit but the grids will stop the gravel all ending up down the bottom of the garden.