It was lovely route, taking in a few seaside resorts, Sandringham and inland lanes. 4 days will be pushing the pace if you dont want to stop and see the sights.
I'm glad you liked it, but King's Lynn to Wells mostly follows the Norfolk coast cycleway, part of Sustrans route 1, and misses out some great gravel routes, including the enjoyable Elizabeth Way section on an old railway and the stunning and unusual Ringstead Downs. At some point in the next year, a gravel road should open across the Wild Ken Hill nature reserve of BBC Springwatch fame. It seems the route designer wasn't local, didn't ask any locals and so didn't realise there are permissive routes open across the King's Sandringham estate.
Anyway, it's not a bad route. I'm local and have ridden most of the route over the years, the west more often, except part the bit south immediately of Norwich. I'm happy to answer questions or suggest stops.
Small note: we're expecting a cycleway to be built to the Lynn Premier Inn this year. It'll probably be a farce during the works, but once done, it won't be a choice between riding around a huge dual carriageway junction or making a banned right turn. The
Travelodge is much more central. Friendly independent B&Bs even more so.