Prepare Documents for House Extension

I have a house that I want to extend. As I am not from the building industry I am seeking a suitably qualified and experienced person to assist with: a. designing the extension; and, b. developing a written specification that accurately details the work to be performed These documents will be sent to builders for quotes. You will need to have relevant Australian building experience to prepare the documents. This might suit a retired builder or certifier as you will not be undertaking the actual building work. You do not need to be able to draft as I will engage the services of a draftsperson for this part of the job but you must be able to design and communicate your ideas to a third party. All I am trying to accomplish is to get my message across to builders in a language they will understand so that everybody is quoting on the same thing. You must be able to attend the site which is located in Southport, Queensland, Australia if you can't do this please do not apply. Thank you for your time