Requirements to build duplex

Hi,
I need some tutoring here and it would be very much appreciated if you could give me an answer..

I'm planning to purchase a property (lot size 550m2) and would like to see if I can knock down and build duplex (attached) to live in one and rent out or sell the other.

So, the lot size is 550m2 (R3 zoning) in Newcastle.
As per the Low Rise Housing Diversity Code,
Permissibility? Permitted in R3
Minimum Lot Size? I cannot find the minimum lot size specified for dual occupancies in Newcastle LEP so I assume it's 400m2.
Minimum Lot Width 15m? Yes, 24m
Maximum Building Height 8.5m? Yes, it's 10m

Subdivision part is a headache and I'm confused here..
Torrens title subdivision is only allowed for dual occupancies if the Council allows subdivision in its LEP. Torrens title subdivision is permitted under the Code and the minimum lot size of each resulting lot must be:
- at least the minimum lot size in the relevant council LEP, or
- if the LEP does not specify a minimum lot size, it is 200m2

The lot's minimum lot size is 400m2 as per Newcastle LEP.
Does it mean 400m2 for each duplex and therefore the lot (550m2) cannot be divided?
Can I still build duplex on the lot but I can't sell one of them in the future?

I tried to reach a town planner at the council but they'll be able to come back to me in 24-48 hours...
can't wait for it...

 

Your best bet is to wait.