How do I know if mudguards will fit my 2009 Carrera Kraken?
For your bike I would probably recommend a 'moto style' front fender that uses an expansion fitting in the steerer tube to remain fixed in place. My reason being that it does not look like you have eyelets on that fork for easy full fender installation. 

http://bontrager.com/model/06254 

A seatpost clamp style rear fender is my recommendation. Again, it looks like a full fender set w/ struts would be difficult to mount to your bike (not impossible, just a little finicky) and quite frankly, it would look a wee bit weird to put a full fender on the rear and a moto style on the front. Just sayin'. 

http://bontrager.com/model/06255