I want my main file that is the body of the repository, not to be accessed for writing purpose to the other members of the team, how will i be able to do that?
While it is possible to specify permissions on the repository to control who can write and read the source code, it is not possible to set permissions on a particular file.
Permissions can also be set on branches to protect them from pushing or merging without a pull request. Merge checks are also available to make sure that pull requests satisfy the expected checks before being merged.
Would it be enough to specify the repository and branch permissions for your use case?
Could you clarify how this repository is structured and what is the "main file / body of the repository?