Barbara pretty spot on. Sand on base is best for temporary situation and you can leave it when the pool gets put away for winter. Another way to level is setup up a string line in a square ie. 4 stakes to hold it up and level the string line. Use the string line as a visual guide and you can also measure down from it as you go. As you dig the higher ground, you effectively move it the lower end. Saves having to get rid of dirt and you can restore it to its former natural slope when you returf. Compact the fresh pile at the lower end and use the rubble to help hold it together. Your other problem of turf not growing in that area has little to do with the rubble in my opinion. Does it get plenty of winter sun? Do you feed it/water it regularly? I grew over 20 sq. metres of turf on a cement slab in my yard with only 100mm (10cm) of dirt which also had concrete rubble mixed in. It had no direct sun in winter but still stayed green throughout, beautifully in summer. Good luck.

fill the roundabout with mass plantings. As the view on approach is focused on that fountain, height would only hide it, however it is important on a large scale to play on dimensions of height aswell as depth. So I would plant out the rear of the fountain with a semi circular arrangement of tall plantings, perhaps even trees. Something with delicate foliage like that of a birch grove, so light and perspective can still be seen through them. In from of that a dense planting of hostas wi plenty of foliage variations, height and colour. I would add another urn and topiaried buxus on your garage wall in between each door to match the one visible next to your porch. Repetition and symmetry is an important design element in formal gardens. I would consider balancing the structure with the garden, as it is sparse, and landscaping with much open space will be difficult to achieve a dramatic effect without it. I would have a builder quote to construct a post and beam addition to the front of the garage, bringing out substantial timber rafters out from the wall about a meter, with heavy posts, perhaps even pillars, this would be ideal to paint In a white trim, reminiscent of country estate homes, and provide a gorgeous arbor to plant a white hanging wisteria for example. Draping white blooms from this in spring and summer would look divine, and lighting would further enhance both the fountain garden and the new arbor. Good luck.

Cast a block of concrete, make up a frame to size of base you need, you could tint it if you like, this would be a fast and easy alternative to raise it to the height required add the appropriate holes for the pump and electrical requirements before the concrete sets, have seen this done and it works a treat.

In process of pool works- spotted gum timber deck on one side- light grey bluestone pavers in front of pool shed and on other side. Glass fence. Pool shed was once old garage so kept the shell with lovely curved corrugated iron roof and Tile Cloud tiles on floor.