NateJ95

@Optimus yeah, they would have been getting changed at the next maintenance as I am about to cross 100,000kms on the car. The car is 6 years old at the moment. Had the car serviced twice in the 1.5 years I've had it and no mention it and had everything checked over before I bought it. 
Yeah I was going to be replacing all 4 regardless, the bosch ones are roughly €18 a plug where I am from so I assume a mechanic will try charge me 25/30 per plug. The labour as you said I am expecting 1/2 hours at the moment if it is easy but hopefully not 3/4 hours! 
I am expecting around 275-300 at the moment as a conservative estimate 

Sorry for the delay everyone, had to wait to get a service date, had it in yesterday, techs have said the sound is coming from the way the brakes are worn and suspension itself is fine (first time I have heard that...)