Final answer:
To locate the required reports, you can find them in the Microsoft Service Trust Portal.
Step-by-step explanation:
To locate the penetration test and security assessment reports for the new office in the United Kingdom, you need to go to the Microsoft Service Trust Portal. This portal provides access to various reports related to the security and compliance of Microsoft 365 services. It includes reports like Compliance Manager, Data Loss Prevention (DLP) reports, and Security & Compliance Center.
By accessing the Microsoft Service Trust Portal, you can find the necessary reports for the new office and ensure that the security and compliance requirements are met for the United Kingdom location.