townhouses and subdivision DA Help

Hey, I've recently put a deposit down for a large parcel of land in the western suburbs of Sydney (2800 meters squared), it has a house at the front and a huge backyard. im looking to keep the house and put 6 town houses at the back, I was originally going to subdivide and had got quotes and done all my due diligence in that area but nows it looking like town houses could be a lot more lucrative, can anyone tell me who I would consult to get a DA into council for town houses and how much it would cost just to get me to the DA approval stage and any referrals would be great, thankyou