I am of the opinion that a land division over this site has merit providing that a building designer can achieve compliance with Councils development plan provisions (e.g. site coverage / private open space and on – site parking etc) In the first instance I suggest engaging a reputable surveyor who has experience in the particular Counci and have a contour/site pickup arranged. This survey is essential and is appropriate for design purposes, sewer and finished floor levels and will include identifying significant trees, existing structures and services to assist you with your feasibility. The plan can be given to a building designer to prepare an application for planning assessment.  Once Council has approved or indicated an approval is likely it would then be appropriate to have the designers plans forwarded to the surveyor so he can duplicate and prepare the land division application.  Pursuing your aspirations in this manner and providing a blueprint at the beginning provides council an indicative aspect and certainly prospers your application.

A town planner is not neccessary and will charge fees thats not neccessary nor required.

Talk to a conveyancer,(the surveyor can provide you with a recomendation for sure) about how you should go about a conditional contract.