Where would the constant live be under the bonnet of my 2003 mini Cooper.....

there is a rubber stopper on each side of the front cross frame , screw te passenger side one down until the bonnet fits flat , may have to screw the other up depending on how far out the adjustment was

Behind the radiator in the front of the car under the bonnet (hood)

The hood release is by the drivers left foot rest. To find the release under the hood look at the front grill where the grill starts to bend down on the drivers side under the hood is the release handle.

it sounds like sensor or relay is bad. should replace it. if it fails completly the fan may not come on at all,which would then cause the car to over heat and could cause head to crack.

Thermostat needs replacing..System must be drained and new thermostat installed and refilled.

My front wipers stopped working checked fuses then realys then took out the motor everything is checking out ok apart from no power to the fuse box under the bonnet any help welcome.

In the S model it's in the boot under the floor mat.
In the standard model it's under the bonnet on the left sidr of the car (US Drivers side) You'll see the cables going into the plastic battery box.

the pump is also a computer may need a new pump

that whining noise is definately your power steering pump. the earlier models eg 2001-2003 just have noisy ones. so they say, if that noise become really excessive; its an early warning that its gonna fail. the newer pumps are much quiter, but i was quoted approx 1200+ CND for a new pump. I have a 2003 cooper, and the whining noise is loud. only once has the steering been really stiff, but i resolve that problem by restarting the vehicle. watch out tho, the power sttering could fail on you while your driving around a corner, and if you dont have both hands on the wheel, you'll go strait.