What is a "personal tutor"?
In the UK, a personal tutor is assigned to you when you start your degree and the same person will generally maintain that role for the whole of your course. They are usually a lecturer or more senior-- never a student, PhD or otherwise. There are often a mandated number of meetings that a student must have with their tutor: once a term is common.

The role of a personal tutor is mostly non-academic. While you could discuss academic problems with them, they are really there to help with pastoral matters, such as wellbeing, or helping you to decide what courses to take or how best to manage your time. Personal tutors are a common choice of reference letter writers for their students' applications for postgraduate degrees, as they likely know the student and their grades very well.