Garden levelling

[skybluescooby]

I plan to remove my rear lawn in September and re build the whole area as it is un even, bumpy and slopes. Having had a garden room built and installed a new patio this year the area that the garden drained down to is now a patio so the garden just floods and as its a clay base it stays wet for weeks.

So how do i do it.

The garden is approx 12 mtr wide by 10 mtr long and runs down hill from top left of garden to bottom left with a fall of say 0.5mtr in 12mtr.

My idea is to remove all the grass and skip it, import tonnes of topsoil and lay new turf with a fall to the trees i have installed at the back of the garden.

Now do i do as i have said or could i just rotovate whats there and bring in topsoil to level ???
Or could i just pile topsoil on whats there already and lay new turf on top of that ????
Got a lot of time to think about this one plus i'm currently building small walls around the garden to hold the soil at the new level
?

 

[WabbitPoo]

just piling topsoil in a slope away from the house wont work because it'll drain tgru that and will run over the old clay base as before. Do all you say but also install a strip drain to divert water away from the patio.

 

[skybluescooby]

Cheers,
Excuse my ignorance, but a strip drain ?
Plus would it be a good idea to mix in some sharp sand with the topsoil > If so, are there any guidelines as to the amount