Late morning, or after the confirmed liturgy
Plan on ER estimate: 45–60 minutes, more for worship or restricted entry.
Go to the cave before spending the day’s remaining attention on another large church. Thomas’s remembered refuge changes the scale of the pilgrimage. Allow a short, unhurried visit to the old chapel, then enter the parish church if open; the cave is a place for prayer, not a queue of objects to photograph.
Give your time to The old chapel and cave when accessible, followed by prayer in the living parish church.
If the cave is closed or unsuitable, pray in the chapel or parish church. Avoid promising entry from office hours.
If the day runs short: Keep the old chapel; omit the circuit of subsidiary features.