The examiner gave me back both forms (both the application form and the test report),
An Application Form (in this case SRG1119C) is not required as the Test Report (SRG1157) serves the same purpose - however no harm if both are submitted.
But a
Course Completion Certificate (usually SRG1107 for SEP but, as MJ states, an SRG1119D is acceptable)
is mandatory.
Have you got a Course Completion Certificate?
I don't really have any experience dealing with renewing or revalidating licences and ratings
And you are not expected to, that is an Examiner's job. Just make sure you understand the requirements to remain legal now that your SEP is Renewed.
It is a
requirement on Examiners (not on examinees) to send back to the CAA any Licensing Paperwork within 14 Days.
Giving it to the candidate and asking them to post it is, as we see in this case, fraught with pitfalls. Much easier for the Examiner to just scan them and send them electronically themselves to the CAA