You probably don't need to turn over the soil--probably shouldn't on a steep slope. Talk with your local experts about the best way to convert your paddock. Maybe there are enough native wildflowers growing in there that you could manage by not mowing. Here in the US Midwest we often solarize the soil by covering it with clear plastic sealed all around--this takes a full summer. I have also killed grass by covering it with a tarp for a whole year. For paths I have just laid newspaper, wetted it, and then covered it with mulch. So, it really depends on how big the area is that you are considering. Do find an expert on your area.

A local garden store or designer will certainly be able to help you. In the meantime, you can look up ideas online, but you'll need to know some basic information before anyone can help you choose specific plants. The first and most important is to know your planting zone, which is all about your location and climate. You also need to know the directional orientation of your house and the wall, and whether it is "full sun", "partial sun", or "shade". Will you be planting on both sides of the wall? You may wind up with vastly different plants if one side gets full sun and the other is in the shade. Take into consideration whatever shade is cast by the large tree, and the house itself. If you have the time, spend a day taking pictures of both sides of the wall - maybe once an hour (shadows will shift somewhat throughout the season), so you may want to do this every few weeks and keep a visual log of how the shadows move. Also, before you plant, decide if you want to paint the wall. It will be easier to paint before you plant, of course. White will reflect heat back onto plants. Climbing plants would look nice on the wall, if you're not going with a very structured garden. Ivy is an obvious choice, but there are other vines that flower beautifully, if you like that idea.

Park in on street parking and use your designated parking spot for container veggies. If the other dwellers won't poach them. Contact a local garden club to pair up with an older gardener who may have to be cutting back her pursuits but isn't ready to give up gardening all together. That's win/win. Maybe a local food bank is trying to get a gardener's donation initiative off the ground and needs help convincing local gardeners to ''plant an extra row'' for them. Or Habitat For Humanity might be interested in doing edible landscaping for some of their homes and people who have never gardened before and who might need help. Lots of ways to have green fingers if you really want. If none of those initiatives exist in your community, then initiate them yourself!

We solve this issue with our clients all of the time with outdoor water features. We recommend getting a water wall that is suitable for both indoor and outdoor use. Not only will they drown out the noise but will also act as a nice privacy wall. https://www.soothingwalls.com/outdoor-fountains/glass-outdoor-fountains.html