They usually ask to see your final report, from your placement supervisor and your practice educator, instead of a reference.
The interviews can be different depending on which local authority you are applying for, some have just 1 interview. Some have interviews, written exercises and children panel interviews.
The types of questions that you may be asked, basics such as knowledge of legislation and policy, knowledge of Section 17 and 47, accurate record keeping etc. The job descriptions and person specs will give you more information on your role.