After five years, 10,000 plants uprooted and replanted, 15,000 panes of glass replaced, 69,000 sections of metal, stone and timber repaired or replaced, enough scaffolding to stretch the length of the M25, and £41m spent, the largest Victorian glasshouse in the world is ready to open its doors again. The Temperate House in Kew Gardens is once again, as Sir David Attenborough describes it, ‘a breathtakingly beautiful space’