I used to live in Norwich and fished the Wensum and the Yare. The Broads themselves don't really start until you get to Surlingham on the Yare.
There are some large Carp in the Yare, but locating them is a real nightmare, the biggest I have heard landed was a Mirror of 35lb from Thorpe. They are all along the River though, from the junction with the Wensum, all the way down through Thorpe, Postwich Woods End and down
New Mills Yard on the Wensum is a possible, but getting into there you need a boat. For Carp try further upriver, by Dolphin Bridge and up behind the Anglian Water Station, I know for a fact that there are some big Carp along there that escaped from the fish farm at Hellesdon.