Since Faye Georgiou is SO much in Demand, she may already be booked for Your date. Despair not! The best-regarded GROUP tour agency for Athens is Athens-Walks... but they ALSO provide personal tours w a licensed guide at a time you specify. DO take Carol seriously ... it is VERY important, if going in the AM, to beat the huge throngs ... you need to get in at 8 AM or 8:15 if possible, if any slots are left... because about 9 am all the tour ageny groups pour in, PLUS huge groups from Cruises.
If no slots left, early enough to beat the crowds, try a reverse strategy -- look for entry slots about 4 pm, when numbers dwindle ... Acropolis is open until 8 (they start pushing u out about 7:30). In that case, you could go in the AM to the Acropolis Museum, and see the artworks & treasures first.
PS: for light meal before or after your Acropolis visit, the Museum has a great glassed-in terrace cafe, where you can look up at Parthenon while you snack ... good prices too, AND you can visit cafe even without buying ticket for museum.
If you haven't already secured an entry time, you might be able to use Athens-Walks services -- you could email them & say you want their pvt guide service at Acrop for 2 hrs ... and say u dont have entry times yet, could they handle it? FIrst pref, 8 or 8:15, or if not available, then 4 pm. Won't hurt to ask .. they have good service reputation..