Looking at the route the Shere cafe really is the obvious place to stop.
The route is 116km in total. We pass through Shere at 50km and then very close to it at 66kms, after we've done a 16km loop over Holmbury Hill and back via Pitch Hill.
Assuming a 9.45 start and a 15mph/24kmph average (it's hilly), then we'll pass through Shere the first time between 11.45 and 12.00 and the second time (with a slight detour) around 12.45 to 13.00. There are also shops in Shere and at Peaslake on the HolmburyHill/Pitch Hill loop, so we could aim to be at Shere for a cafe stop between 12.45 and 13.00, but with the option of picking up a snack or drinks at one of the shops in Peaslake or Shere before then, if we need them.
If we took the longer option and stopped at 66kms, then that leave just 50kms to complete the ride when we leave the cafe. That leaves 4 main climbs in the last 50kms, Farley Green, Barhatch Lane, Coombe Bottom and Crocknorth Lane. We also pass back through Shere at 98kms which gives us another chance to pick up refreshments.
How does that sound?