Thanks for your question, Mick.
Not only is the Leader of the Opposition allowed to debate in the Australian Parliament, it is encouraged and expected that they will do so!
They take the lead in opposition debate on bills—proposed laws—and critique government policy that the opposition disagrees with.
The Leader of the Opposition also directs questions to the government during Question Time, where they normally ask the first question of the day.
If the Prime Minister makes a speech to the House, the Leader of the Opposition usually has the right of reply, which means being given equal time to speak on the issue.
As well as representing the people of their electorate, the Leader of the Opposition has many other responsibilities which you can read about in this fact sheet.