So following the issue with the radiator I had taken the car on a couple of small drives just to feel things out and make sure everything was working properly.
One thing I did notice on a drive was that the throttle was acting up, one minute it would idle too low, the next too high. So I got to inspecting and found quite quickly that the adjustment nuts on the cable and the thread they worked on were knackered. The threads were chewed up and as a result it was near impossible to set the tension on the cable correctly.
I knew this probably wasn't the cause of all of my idling problems but it definitely wouldn't be helping!
So I ordered a new one, and got it fitted! This was a pretty straight forward process you had to un-attach the cable from the pedal first, then un screw two nuts on the firewall. Once you'd done this all that is left is to unclip the cable from the throttle body and pull everything back into the cockpit.
Fitting the new one was equally straight forward, simply performing the same steps in reverse, and then adjusting the cable to set the tension.
The low idling issue is now gone, however the high idle when you stop at junctions is still there albeit intermittent.