Help with soil

Hi All,

I have just had the backyard done. I have left plenty of space to plant lots of things but mainly vegies and my bonsai trees for early growth before i can move them to pots.

The landacape guy didnt fill it enough i believe so now i want to fill this space to a certain level.

The question is where do i get the soil? Like should i get bags from bunnings? I am sure it would take lots of bags or should i order like a truck load from somewhere? Thank you

https://imgur.com/a/S8pvlVj

EDIT: I am located in Northern Victoria (Donnybrook)