Countryfile's Plant Britain autumn special celebrates the magic of trees and hedgerows in combatting climate change, boosting wildlife and our own wellbeing. We also look at the future guardians of our planet as Charlotte Smith finds out about green careers and Matt Baker meets a six-year-old environmentalist with big ambitions. Tom Heap joins the front line in the fight against tree disease, John Craven is at Westonbirt Arboretum to discover what our future forests could look like, and Joe Crowley is busy learning how to collect and sow seeds. Margherita Taylor pops into a Bristol community garden to help them get ready for winter, and there are some special messages from well-known faces to encourage us all to plant Britain.