I have enrolled as a PhD student in one of the UK's universities. I have been received an email containing a list of different professors and secretaries in the department. I am a little worried since I don't know how to greet them and I don't know what to say. Could anyone please help me?
I disagree slightly with SolarMike's answer. The academic hierarchy in the UK is very informal. It is fine to use first names for everyone, be they professor, admin staff or cleaner. A simple "Hi Bob" is fine in emails or in person.
I would argue that it would actually be a bit strange to address someone by their title and last name. If you did so, I expect they would quickly tell you it's fine to address them by first name.
Good morning Dr Jones or Good afternoon Professor Smith usually works fine.
And, based on comments, Mr/Mrs Smith or the first names as applicable (and that can be the faculty/professors as well). However, making the effort to talk to those who look after the infrastructure at any level does pay dividends...
Even when equipment is being got rid of by another department you can get to hear of it first and "appropriate" it... :)