Here are some useful links:

Canterbury
 - Visit Canterbury: https://www.canterbury.co.uk/

Outdoor Activities:
 - Canoe Wild: https://www.canoewild.co.uk/
 - TrAles of the Unexpected: https://www.tralesoftheunexpected.co.uk/

Rambling and Walking:
 - The Ramblers Association: https://www.ramblers.org.uk/ 
 - The Open Spaces Society: https://www.oss.org.uk/