Next week (up to 7 days from 5 July) a section of National Cycle Route 1/11 just south of King's Lynn will be closed for resurfacing (Norfolk County Council reference WTRO 1954).
For National 1 in either direction, stay on the bigger road (Lynn Road) between Saddlebow bridge and Wiggenhall St Germans - National 1 will rejoin you at either end of the diversion. For National 11 southbound, do the same but turn left into Mill Road just after entering St Germans and National 11 starts from the Watlington turn. For National 11 northbound, follow the signposted diversion.
The closed section is approximately this and north to the roundabout https://www.openstreetmap.org/way/9710186#layers=C