Right had a good look now the weather calmed down. The first 2 spark plug chambers were full of water. I have cleaned these out and the car seems much better, had a few blips still but i assume this is because i couldn't quite get all the water. Im hoping it is rain water as apposed to coolant.
I would imagine the knock sensor was triggered through excess vibration in the engine caused by a slight misfire? However this error is no longer present since installing a new sensor, but i did not know about the water in the chambers before changing the sensor so no idea if it were dodgy or excess vibration.