Thanks for the answers guys.
I currently have the sensor at the thermostat housing(replasing the stock sensor) but it does not read temperature properly.
Maybe because the thermostat is close until a certain temperature,i dont know.
Although it is not good practice to remove the stock sensor, that is where I mounted the sensor for my gauge. I did take the precaution of wiring in a seperate manual switch so I could flick the fan on if required. I had intended modifying a spare thermostat housing to take both sensors, but since I have never had to put the fan on, (other than to test it), I have not got round to it.
As said earlier mine sits at 80 degrees nearly all the time. It rises about 4 or 5 degrees after stopping due to heat soak from the engine with no water circulation.
The standard fan switch and warning light switches are supposed to kick in at 102 t0 108 degrees.
Below is a photo of where I mounted the gauge and manual switch from a bracket picking up the mirror mounting studs. Ignore the tube bracket above the clocks, that's for my satnav.