If you look at CAP1721 it will list an alternative means of compliance which reduces the FI Course to 30 hours of ground training and 15 hours of flight training followed by an Assessment of Competence. To add the IRI and CRI(ME) you will need to complete the courses listed in Subpart J.
This is correct in the first instance. However, once the applicant is on the course, this training requirement can then be reduced further to training as required in accordance with Article 3(b) of Commission Delegated Regulation (EU) 2020/723 within UK Part-FCL/EASA Part-FCL.
A point to consider is what do you want to teach? PPL or Commercial, the latter may present more of a problem as the UK will not be an EASA State after 31st December and to train for an EASA licence will require an EASA instructor; UK instructors will no longer be EASA instructors.
As holder of a UK instructor certificate, it's possible to teach on an EASA course providing the ATO holds the relevant EASA course approval; as holder of a third-country instructor certificate, instructors can
apply to an EASA NAA for issue of an instructor certificate in accordance with FCL.900(c).
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