Limiting access during holidays

Is there a way to deny access to users during holidays, provided that they were registered in the system’s holiday list?

To deny access, you need to disable the user you want and enable it when you want him to access
If you want to link it and deny users who are registered in holiday list then you need to make some customization

You can limit access to a certain IP address if you want. This is available in Security Settings section in the User Profile.