Posted: 17/02/2015 at 10:02
Someone else has done all the hard expensive landscaping. It may be that the builder has dumped the clay subsoil on top of the decent stuff. If you can incorporate as much organic matter as you can in , and fork it through the soil, it would give you a good start. You can use compost, well rotted manure or fine shredded bark. Some garden centres sell bags of soil improver, which to my mind is expensive, but if that is all you can get, it will do.
All the walls could be cloaked with climbers such as honeysuckle, clematis, or jasmine.
The beds could have seasonal bedding in for a year or two, until you decide what perennials you want. That gives you more time for soil improvement.