A pond, even a small one. Water is the single most valuable wildlife feature you can add to a garden of any size. Even a half-barrel pond will support frogs, insects, and drinking birds within a season. A properly designed pond, with gently sloping sides and planting cover, will bring more life than almost anything else.
Native and near-native planting. Hawthorn hedges, foxgloves, aquilegias, native willowherbs. Ecologically rich and beautiful. Wildlife value and visual quality aren't in tension if you know which plants to choose. I do.
A quiet corner. Leave somewhere alone. A log pile in a shaded area, a patch of longer grass, an undisturbed edge beneath a hedge. These require nothing from you, and provide a great deal to the creatures that use them.
A water source. Even a shallow dish of water beneath a shady shrub will bring birds, bees, and hedgehogs. It costs almost nothing and makes a surprising difference through dry summers.
Reducing chemicals. I recommend avoiding pesticides and herbicides wherever possible. There are effective alternatives for most garden problems that don't affect the wider ecology of the space. This is something we can discuss during your consultation.
Hedgehog access. Hedgehog populations have declined dramatically across Yorkshire in recent decades. A gap of 13 centimetres at the base of a fence or wall (no larger than a CD case) allows hedgehogs to pass through and connect with neighbouring gardens. It's one of the simplest things you can do.