Perhaps simplest, XLC, to post the regulation, exactly, word for word.
You'll see there's no CAA, or any other National Authority, involvement at all.
FCL.740 Validity and renewal of class and type ratings
(a) The period of validity of class and type ratings shall be 1 year, except for single-pilot single-engine class ratings, for which the period of validity shall be 2 years, unless otherwise determined by the operational suitability data, established in accordance with Part-21.
(b) Renewal. If a class or type rating has expired, the applicant shall:
(1) take refresher training at an ATO, when necessary to reach the level of proficiency necessary to safely operate the relevant class or type of aircraft; and
(2) pass a proficiency check in accordance with Appendix 9 to this Part.
There's another clause with just a slight bearing on it:
FCL.015 Application and issue, revalidation and renewal of licences, ratings and certificates
(a) An application for the issue, revalidation or renewal of pilot licences and associated ratings and certificates shall be submitted to the competent authority in a form and manner established by this authority
........
The deal here is that your renewal itself will be done by the examiner, on the Authority's behalf, thus it is the examiner you apply to.
Once all done, the CAA will be told via a (ridiculous) form.