Boudicca Way is the long-distance walking route between Norwich and Diss, roughly following the old Roman line through South Norfolk. You do not need to walk all 36 miles for it to be useful: the Diss end gives easy access to quiet fields, lanes, and border-country villages.
For a short outing, pick a section with a bus, rail, or taxi plan rather than assuming circular walks are obvious. The countryside is gentle, but the navigation rewards a map.