Here's a brief description and location of the cells. The problem is that people refer to the "Sahara" cell - but two cells were adapted for the filming of Sahara so it adds to the confusion.
Cells 1 & 2: These are located in the centre of the site with the huge "Exhaust Silencer" concrete tower behind them. I've seen lots of pictures of the control room for these cells (with "Pyestock" punched out of the control panel and the "Star Trek" console); but hardly any of the interiors of the test cells themselves nor inside the Exhaust Silencer (which is like a huge concrete bunker).
Cell 3: This is the small cell with the "Sahara Doors" The adventerous will discover that there are walkways and tunnels deeper than the cell, and they eventually lead to flooded areas to the west. Cell 3 is actually much larger than just the "Sahara Doors" and continues west, under the Air House pipe array, and onwards to Cell 3 West.
Cell 3 West: This is the huge circular cell with the large white plastic opening that everyone likes to take pictures of themselves standing in. It's normally the first thing people find when getting into Pyestock.
CEGB Transformer Park: The large, humming transformer park to the south of Cell 3 West.
Cell 4: This is also known as "Sahara" and is the huge test cell to the south of the Sigma building. If you climb deep into its bowels (there are large tunnels with steps), you find lots of "Emergency Alarm" switches which probably correspond with the light panel in the control room.
Air House: I think everyone knows this one.
Plant House: This is the large brick building to the east of the Air House. It houses the three huge halls with the Metrovick equipment, control room to the west and offices to the east. To the sides of the halls are lots of individual test cells including the largest which is called Cathedral.
Battle House: The large building on the northern edge of Fairbanks Transformer Park. It looks absolutely stuffed full of heavy plant equipment because... well it is. Battle is to the east of Cells 1&2
Fairbanks Transformer Park: Now just a huge expanse of gravel, it forms the centre square of three important buildings:
Power Station: On the south edge of Fairbanks. Small turbine hall, fantastic control room, offices, battery room and more.
Admirality Test Cell: The large building on the east edge of Fairbanks. I've not been in here yet.
Hope that helps!
All the best,
Simon