Hello there,
I am working on a healthcare application aimed at streamlining patient data management for small to medium-sized clinics. As part of this project; I am exploring the integration of FHIR standards to ensure compatibility and interoperability with existing NHS systems.
What are the key factors to consider when implementing FHIR standards in a custom healthcare application? Are there specific resources or libraries you recommend for developers who are new to FHIR?
Given the sensitivity of patient data, what are the best practices for ensuring that the integration of FHIR complies with NHS data security standards and GDPR regulations? 
Are there any common pitfalls to avoid?
How can I ensure seamless interoperability between my application and existing NHS systems? Are there particular FHIR profiles or extensions that are commonly used within the NHS that I should be aware of?
What tools or frameworks do you recommend for testing and validating FHIR implementation within a healthcare application? Is there a sandbox environment available for developers to test against NHS systems?
Also, I have gone through this post; https://developer.community.nhs.uk/t/question-about-rp-initated-logout-end-session-endpoint-mlops/ which definitely helped me out a lot.
I am keen to build an application that not only meets the needs of clinics but also aligns with NHS standards.
Thank you in advance for your help and assistance. 