International Faculty of University of Sheffield is great in terms of value and what it offers. I can name a dozen of great professors and lecturers who all have open door policy and are more than welcome to help. Classes are small and enable a student to participate in everyday interactions, which in my opinion is the best way to learn.
Thessaloniki is also a plus, being at such nice city while studying is great. The only criticism I have is that in the past few years entry requirements standards have been lowered and as a consequence, there are students who have really poor English, and due to who quality of classes suffers. I think that some filter of quality must exist for uni to keep its reputation. So keep your standards high as before, and everything
will be fine.