Just to throw another option into the melting pot. Not NE Norfolk but not too far of a drive. Strumpshaw fen.
Clicky 1 It is an amazing reserve and if you stay till dusk you can walk up and watch the rooks coming in to roost at Buckenham carrs
Clicky 2
A good clip of the Rooks
Clicky 3
Wherever you decide to go Norfolk is a stunning place to visit and always throws up some stunning sightings. Keep your bins to hand at all times.