This is a dead easy job, but interestingly I have noticed that some "full dealership service history" cars haven't had then changed!!!
The fliter is located in the grill that runs along the bottom of the front screen on the nearside. To remove the cover push the two top tabs towards you while swinging it open
Then flip down the filter houing lid towards you
Then pull out the old filter and insert a new one, making sure you get the flow arrows the correct way round
Then just close the lid and replace the grill.........Job done...easy!!
I have seen these filters blocked with allsorts, including bumblebee's, toffee papers and in one case some sort of seed which had started to grow!
I change my filter every 12 months, and find it pretty well blocked each time, but as its so easy to remove you can check on it any time