Have only done QF98 in J recently and have refused to take QF97 since it was re-timed to an overnight flight. However, based on my experience with such QF overnight flights I would expect a "dinner" meal service aftetr take-off with the usual choice of 2 hot dishes with a small plastic tub of salad, a "bread" roll and dessert and maybe a mini chocolate bar. Then 1.5 to 2 hours before landing expect a "continental" breakfast.
If you want to maximise sleep opportunity, then eat dinner before departure, don some eye shades and pull up the blanket and you should not be disturbed.