Tutorial times will sometimes vary based on meetings, duty, absences, etc. that are often unavoidable. It is always best to let your teacher know ahead of time that you plan to be at their tutorials.
Appointments should always be made at least 24 hours ahead of time.
You are fully able to attend the tutorials of a teacher who is not your teacher of record. If you are only able to attend tutorials with a different teacher, you should still go and get your work done.Â