Thame CC has a page on the RidewithGPS website which can be found here. There is a collection of routes to choose from to be used by Ride Leaders or if you go off on your own. Another option is to search on RidewithGPS website for routes starting in Thame, you will find plenty of routes created by Ride Leaders from the club.
Thame CC takes no responsibility on how accurate the routes are and for the road conditions. Use at your own discretion.
Below are a couple of links of routes from the past. All of these can be found on the Thame CC page also.