Hi John
Apologies for not coming back to this earlier, been doing my bit trying to keep Saltaire Brewery in production
Mooring in Norwich is thorny one. We have moored there many times without any problems. However I think it would be wise to avoid Friday and Saturday nights. We had a lengthy conversation with the ranger there in the summer. I forget the exact figures but he said that out of x thousand boats that had moored there only a handful (single figures) had experience any problems. It might also be worth considering mooring nearer Bishops Bridge where the river is further away from the road.
Mooring at Thorpe is a possible but you need to be careful not to get stuck because of the bridges. Another option we have tried is moor at Commissioners Cut which is just downstream from Thorpe. A track leads from the back of the cut, over the railway and out onto the main road. It should be possible to get a bus or taxi into Norwich. Even at Norfolk prices, a taxi should be under a tenner. Another option would be to moor at Cantley and catch the train. The station is only a few minutes walk from the moorings.