Specrite Multi Use Panel 1800×405×18mm (Brown, Golden Teak, Hevea) – $29 (Was $59) C&C @ Bunnings (Excl WA)

Credits to price hipster.

Great little panels. I used two of the 60cm deep ones (these are 40) to make some two new desks at home.
YMMV but the workshop out back will help you cut it to size if required (first cut free). I kept the off cuts and used it as monitor raisers with some 3d printed legs.

If using as a desk topper you’ll want to either sand down the edge (its pretty sharp) or get a decent desk pad (I have the nordic one from amazon).

Stock varies store to store, either check via website or using your stock checker of choice,

Eg link for stock checker for the golden teak