Cambridge has generously provided a complete practice test with answers.
Download a full test here:
Under the table that summarises the different parts of the exam, you will see some lines of text. Find the line that says “+ Where can I find sample papers?” If you click on this text, a new line will appear that says “You can find sample papers for Cambridge English: Advanced (CAE) here”. If you click on this text, you will download a .zip file which contains a full exam, including the audio files for the listening paper and an answer key.