Thanks for the prompt response guys!
The overheating happened on Friday and the car had really been stuck in traffic for a few hours, the needle went almost to the top before I opened the bonnet and let her cool down.
Good news that its not the water pump, its not the fan as that does cut in.
I have tried listening for the noise but can't seem to track it down, I will try and look at the belt and the tensioner this weekend.