I really don't think adding more houses to this area is appropriate for the welfare and sate of Hellesdon. Schools, doctors and dentists etc are already overcrowded and difficult to get in to. Traffic congestion added to this area would also be unfair to the local residents, who also have to contend with people parking in the area to use schools, shops and the airport.
The best use of this land would be to open as recreational ground and to make it a community area, where there can be play areas, make use of the pavilion, contact organisations who can rent for events such as fitness classes and parties etc. There isn't a park on that side of the Cromer Road for children to use or for people to walk their dogs. At the very least give it a go at this first. I am sure it would be a welcome addition and keep the area green, even use some of the land to plant new tress for wildlife etc.
The tennis courts could be rented out to generate revenue as the pavilion.
You only have to look at the likes of Eaton park to see what can be done, but this side of the city.