Hello @Paul Costelloe
Thank you for reaching out to the Microsoft Q&A platform. Happy to answer your question
Azure Advisor is a suitable place to start for help with Azure capacity planning. It provides recommendations for optimizing your cloud investment, reducing costs, and evaluating where your money is being spent. Azure Advisor can identify virtual machines with low utilization and provide recommendations for reserved instance purchases Additionally, Azure has many discounts that your organization can take advantage of to save money, such as Azure savings plan for compute and Azure Reservations.
You can find more information about these discounts in the article "Optimize your cloud investment with Cost Management" at the following link:
How to optimize your cloud investment with Cost Management
Please accept as answer and upvote if the above information is helpful for the benefit of the community.
If you have any further questions, feel free to tag me in the comments.