Hi @raymondmarshall,
Thank you for your question and welcome to the Bunnings Workshop community.
Firstly, I would use a Rotary Tiller to turn and aerate the soil. This will allow any products and the root growth of any grass to penetrate deeper into the soil. Please note that you should contact your local store to check for availability of the rotary tiller that I have linked to.
I would then suggest applying Richgro 15kg Natural Gypsum Clay Breaker in a suitable quantity for the area. This will help to break up any clay allowing for better drainage and root growth.
You should also add a sufficient amount of topsoil, such as Scotts Organic Lawn Soil Topdress & Underlay to enhance the nutrients in the soil and promote growth.
You might also like to have a look at these articles for some guidance on growing and preparing for turf:
If you have any further questions, please don't hesitate to ask.
Jacob
