The requirements for training documents are stated in UK CAA Standards Document 55, Paragraph 14.1. This includes a detailed list of what must be included in training records, who should see them and what should happen when/if a student moves to a different training provider. The same material is undoubtedly included in some EASA document, but the Standards Document is easier to find.
The document includes the following statement:
"Students are required to sign each report acknowledging the debrief"
Refusing to permit students to read everything that is written in their records is likely to foster a culture of distrust.
The full document is available on the CAA website.