There are a number of excellent resources to find walking routes. Here are some that are worth looking at.
Ramblers Routes is the Ramblers' own database of walking routes. You will need to register on the site to access the full range of walks.
CWW supports the Chiltern Society and they have a number of maps available in paper format or maps and routes which can be downloaded.
These walks around Chesham have been created with an accompanying set of well-designed and attractive leaflets to guide you on your way.