chr1staylor

Nope, gotta be done from underneath, it's buried right up behind the engine. The undertray is just a piece of thick plastic, held on by 15-20 T25 torx screws if I recall correctly, with some locating points at the front to join it to the bottom of the front bumper. Straight-forward to remove if a little time-consuming.
 
Need to get the car up to a decent height too, on ramps at least so you can move your elbows around as you'll need to get your hands at quite specific angles for access as there's a drive shaft right in the way.
 
It's held on by three allen bolts, two of which are easy enough to access but the third is a bit awkward, essentially it's on the far side of the valve and you can't really see it so have to access it by feel. We had to fashion a longer allen key by cutting the "L" off a standard one and locating it in its own socket which I could ratchet.
 
The connector to it can be a bit fiddly to undo too, but if you have a look at the replacement valve you'll see how it connects so you can work out where to squeeze the connector off the original.
 
 
Edit: good video here of where it's located: https://www.youtube.com/watch?v=BiBqDcWSYCU