On Day One, we walked from Reading to Mortimer which is 11.5 miles along the Kennet & Avon Canal, through fields and lovely woods near Burghfield Common, finishing in Mortimer, approx 5 hours later (without stops).
We collected a stamp from Reading Museum (guidebook and passport available there), explored the Abbey Ruins which were a place of pilgrimage themselves in medieval times, and then headed along the Kennet and Avon through the Oracle's restaurant area and fairly quickly out of Reading. In the Reading town centre section, make sure you pay close attention to the waymarking as you cross King's Road and also Duke Street, as it is easy to miss. But basically you are following the watercourse.
There are several pubs en route for refreshments/ to collect pilgrim stamps including the Cunning Man (4 miles from Reading and lovely garden) and the Fox and Hounds in Sheffield Bottom (good coffee).
We returned to Reading at the end of Day One on the Number 3 bus from Mortimer (regular service/takes about 30 minutes).