Helen and Kevin are nearing full retirement and have a garden dominated by three things — a patio that looks too big for the space, a breeze-block wall that looks ugly and a shed that sticks out like a sore thumb. Inspired by Portugal's granite stone sets and raised boardwalks, they like the idea of a low-maintenance seaside garden with little or no lawn and drought-resistant plants like thistles and grasses. With a budget of £4,000, Charlie and Lee have a challenge ahead to craft this coastal oasis despite being a hundred miles from the sea.