Seriously....... It's dead simple. We are a UK school in Spain and train people from all over the EU without problem.
You will need to get a course completion certificate from the ATO after the Head of Training decides what your refresher requirements are. The examiner reads the EASA examiner differences document and notifies the CAA of the test if a noN UK Examiner. After the test the SRG1157 foes to the CAA along with the course completion certificate and a copy of the ATO approval. The examiner signs your licence and logbook and that's the job done.
It's simple and easy.