Generally speaking, IPT is a subject that you can perform well in without a tutor. However, students are different in terms of their learning and academic capabilities. This means that whether you need a tutor depends on your own circumstances. You mentioned that you struggle with context diagrams and data flow diagrams. While both are important concepts that are regularly assessed in IPT HSC exams, they do not constitute a large part of the subject's content, and you can definitely work on improving your understanding of both concepts. Being the last IPT cohort, you have correctly identified that your cohort will have the most resources, and you should therefore use that to your advantage. If you are not facing more serious issues with the subject (for example, if you are not facing difficulties with a more significant part of IPT content), I think that you do not need a tutor at this stage.
In terms of the specific concepts, context diagrams represent an overview of the entire information system. It is shown as a single process (circle) along with inputs/outputs (arrows) and external entities (rectangles). On the other hand, data flow diagrams represent an information system as a number of processes that together form the system. They are more complex than context diagrams as they provide a further level of detail not seen in context diagrams. This complexity can also be a way through which you can distinguish between context diagrams and data flow diagrams. The elements in a data flow diagram remain similar to those of a context diagram, with the addition of a data store (open-ended rectangle). Essentially, context diagrams and data flow diagrams can support the process and understanding of system requirements.
I hope this helps!