I have published an open-source PHP reference implementation showing how a micro-entity accounts filing can be prepared as iXBRL and submitted through the Companies House XML Gateway.
The project is intended to help developers understand the complete workflow, including generating the iXBRL document, creating the submission envelope, polling for the result and acknowledging the final status.
Others are welcome to inspect, adapt and learn from the code for their own purposes:
https://github.com/ibizara/CompaniesHouse-iXBRL
It is an independent project and is not endorsed or supported by Companies House. Users remain responsible for the accuracy of their accounts, eligibility to use the relevant accounting regime, taxonomy compatibility, security and compliance with the current Companies House technical specifications.
The repository does not include presenter credentials, company authentication details or filing data. Users must obtain and configure their own credentials.
The current example focuses on micro-entity accounts and is intended as a technical demonstration rather than accounting or legal advice.