Just for information, you don't technically need to replace it. If all you're worried about is legality, then there's no issue: the front fogs are not "required" lights, so they can be cracked, broken or simply not working. My old Peugeot 106 went through 2 MOT tests with one of the front fogs completely broken (it actually had some bits of glass still attached to the reflector). It passed without problems.
Of course, if you want to replace it anyway then that's fair enough.