Hi @beanieg,
Thank you for your question and welcome to the Bunnings Workshop community.
I will start by saying that while replacing a fluorescent bulb is a simple task that most people are more than capable of doing, it is still an electrical fixture so there are dangers involved. If you are not confident in your abilities, it may be worth contacting an electrician for assistance.
My advice would be to take the non-working bulb with you to your local Bunnings and ask the team member in the electrical section to help you match it with a new one. You may also need to replace the starters which will be located right near the fluorescent bulbs. The team member should also be able to point you in the right direction as to which starters you will require.
If you have any further questions, please feel free to reach out.
Jacob
