Posted: 20/11/2015 at 15:28
I had a lower level area in my garden round the corner - unfortunately, no pix as it was pre digital camera and we created that by terracing the sloping, grass covered garden. An extension meant the garden was considerably lower than the house, and I often preferred sitting in the lowest part rather then the deck which we created along the rear of the house. It felt very sheltered and secret even though it wasn't!
I think this requires a bit of thought before going ahead with it. It would need to be a paved area like the last pic - gravel if it's on the shady side as it's non slip. Even a small area of soil removed will be a big quantity to shift, so you need to factor in how you get it out. Three metres square dug down a metre is 9 cubic metres. That's a decent skip's worth!
Some pix of your plot, including the rear of the house, would really help vw1978 .