Relocating to the UK as a student - Custom relief

Hi, I will be relocating from the EU to the UK this autumn as a full-time student and am using a international moving company to import my personal belongings. As a student, I will not be able to claim import tax relief via ToR1, rather I am (/the company is) supposed to use the clearance code (CPC) 40 00 C06*. However, in order to be able to use this clearance code I have to provide proof that I am a student. I have not found any information on how to do that anywhere. I received my CAS and have obtained a student visa, but have not yet received my admission/matriculation letter, as I can only matriculate a few weeks before my studies start in October. What proof should I provide showing that I am a student and supposed to use (CPC) 40 00 C06? I have tried to find an answer for this question for days now, reading all the information available on the different .gov websites and even calling HMRC, yet, I have not been able to find a definitive/satisfying answer. All help is appreciated. Kind regards,  *https://www.gov.uk/guidance/transfer-of-residence-to-great-britain#students-moving-to-the-uk-for-full-time-study

Hi katharina,
Please see below guidance on the requirement for additional procedure code C06.
C06: School outfits, educational materials and related household effects
The conditions in transfer of residence to the UK must be met:
Enter the UK to attend a school, college or university for a period of full-time study of at least 12 months.
Provide details of their course and a copy of their offer letter from the education provider with the application/ declaration.
This Additional Procedure Code only grants relief from customs duty.
Where eligible to claim VAT relief, Additional Procedure Code F45 must also be declared in DE 1/11.
Thank you.