Oxford to Covent Garden (central London)

Distance: 102km, altitude: 752m.

https://ridewithgps.com/routes/26861382

My commute to work. Lovely ride to London, taking in Aston Hill as you cross the Chilterns. This route follows the Great Union Canal path for about 12km up to Paddington, cutting out a lot of the traffic in the capital. This tow path is great, and relatively quiet, but not the smoothest surface in the world. Don’t ride with 100+psi.

It’s Christmas (Common) all the time

Distance: 126km, altitude: 1376m.

https://ridewithgps.com/routes/27654394

Fancy taking in some hills? This goes one better than hill-reps. If I am not mistaken, this does not follow the same stretch of road twice (at least not in the same direction), but does tackle the Christmas Common from all directions.
This route includes a tricky descent, see Ride-with-GPS for details.