The building control process in NI requires that you submit your drawings to your local authority for them to be approved as building regulations compliant. Once you notify them you are breaking ground, an inspection regime will be put in place whereby the building control inspector will visit the site at key stages of the build.
In ROI you must file a Commencement Notice; this is done by uploading your construction drawings on the Building Control Management System. Most self–builds, even when supervised by an architect, will opt out of appointing an assigned certifier.
Check the Building Control requirements in your jursidiction.