Had the same thing happen to my 2012 Civic.
Got two fog light assemblies online from Cox Motorparts. They came with instructions. Yours didn't or did you get less parts (mine was with loom, surround etc.)
Anyway, to fit the fog lights, the bumper needs to come off. Which is no fun if you haven't done it before or done similar jobs.
With the bumper off, you can reach everything.
If you only removed the underbody cowels I think you'd have a hard time, but perhaps I'm wrong...
I think there are instructions for the bumper on the
forum: How to section:
How to remove the front bumper - 9G Facelift - Manuals and guide.
(Not allowed to link to it with the post count on my reset account)
I'd reccomend popping the bumper off; Nice and easy that way. Much better than fiddling with screwdrivers under the car, and with the number of bolts / trim clips needed to fully open the access flaps, it's probably faster to drop the bumper too.
If it's the same Valeo unit as OEM (You can get on Amazon for £20!) the H11 bulb connector will just plug in.