Thank you for your thoughtful question! Bilateral relations refer to the cultural, political, and economic (trade) interactions between two countries. In discussing these interactions between any two countries, you’ll want to research a little history of their relationship. Australia was a colony of Britain, for example, so they share a cultural heritage and have a common language. They also share a military and political history, and their economies have been intricately linked for centuries. Canada was also under British rule at various times. The interactions of these countries over time can only be understood in the context of their shared history.
In discussing bilateral relations between two countries, you could focus on trade, politics, culture, or, depending on the scope of your essay, discuss all three of them. The sources linked below provide information and insight on these relationships. Also, as you research, note key words that denote major ideas you might decide to focus on, and then conduct key word searches using these terms. For example, you might search for the terms “Australia,” “Great Britain,” and “trade relations,” or you might search for “Canada,” “Great Britain,” and “cultural exchange.” Do not rely on Wikipedia for a citation, as it is not recognized as a reliable source. However, you can sometimes start with a Wikipedia search to get a general overview of the topic and identify key ideas and terms to search. You can also use an encyclopedia such as the Britannica to get an overview of the topic and focus your essay. After this initial overview, government websites are good sources to consult for primary information on comparative politics.