when in the low flying system
Did you mean the open FIR? As in Class G airspace? No is the answer, most people are in a local area, talking to a FIS or radar service.
There are monitor/squawk frequencies when in the vicinity of major airports in the South East (details fell out of this month's magazines), there is also a "unicom" for uncontrolled fields but there is no centralised frequency that people broadcast on.
Mark 1 Eyeball as mentioned.