It's flat and fast!
From the Civic Centre take Bridge St (cross by bollards at railway bridge with care!)then High St to the Old Green Crossing. Using the subway get onto Clarence Place then Caerleon Rd.
Take Caerleon Rd past shops (taking care to cros side roads)and to M4 junction (care fast traffic leaving/joining roundabout). Continue on Caerleon Rd all the way to the Ship Inn.
This is 3.3 Miles, so you can return the same route to make a 6.6 Mile total.
Alternatively, (taking care when crossing Caerleon Rd by the Ship Inn)run a circuit of the Caerleon one way system. Keep on right hand side pavement passing the Bull getting to the Angel (cross over road at mini roundabout). Continue to Hanbury Arms and back over footbridge to the Ship Inn.
This is 4.5 Miles, so (taking care to cross Caerleon Rd) retracing the outward route makes a 7.8 Mile total.