Hi @Stu Please check the Jira Administrator learning path below, some courses are paid but worth to take to get more understanding about the exam, there are some free training also available you check them as well.
https://university.atlassian.com/student/collection/850385/path/1062304
https://university.atlassian.com/student/catalog/list?category_ids=21734-free-training
Apart from all these video training videos don't forget to go through the official document by downloading the PDF file of it instead searching the each page for every topic
https://confluence.atlassian.com/alldoc/jira-documentation-directory-71598773.html