Inherited situations like this are equal parts exciting and overwhelming, we went through something similar with an old orangery my wife’s family left us. The garden centre glass panes we tried initially looked completely wrong, too clear and modern against the original horticultural glazing that had character even in its cracked state. Ended up browsing completed glass projects after a builder mentioned they handle specialist projects beyond standard windows, and seeing examples of their conservation work gave us confidence they understood the difference between generic glass and proper period-matching glazing. They talked us through diffusion properties for plant growth, not just aesthetics, which honestly hadn’t crossed our minds before. Three seasons in and our tomatoes have never been happier, plus the greenhouse finally looks like it belongs to the house again rather than a patched-up eyesore.