Most garden mistakes are layout mistakes, a patio in the wrong position, borders that block the light, or a path that adds no useful route. The design stage starts with a site survey: measurements, a drainage check, soil assessment, and a sunlight read at different times of day. On Fenland-influenced clay soils, drainage is assessed at the design stage because it affects where surfaces can go and what preparation they need.
The survey output is a scale drawing showing the proposed layout, patio and path positions, lawn area, raised beds, and border planting. For new-build plots in Peterborough, this is often a blank-canvas exercise. For older gardens, it is more commonly a redesign that works around existing trees, levels, or structures worth keeping.
A completed plan lets you see the full scope before any money is spent on materials or groundwork. It also makes phasing straightforward: you can agree which elements to install now and which to defer, with the layout already fixed so later additions join up correctly. That is harder to achieve when design decisions are made on the day the work starts.