When Chris Collins left school aged 16 in the early 1980s, he wasn’t sure where his life was heading. “I just couldn’t sit still in the classroom,” he says. “All I knew was that I wanted to be outside.” Today, Collins has come full circle, dedicating much of his time to championing gardening in schools after jobs including rainforest work in west Africa, garden design in Japan and head gardener at Westminster Abbey. He was…