To be fair until recently I was the same, thought they didn't need to be declared but I'd also never needed to use it. If you go into the bit where you declare any claims/accidents/etc there's generally an option in the drop down for "windscreen/glass claim" these days.Wow didn't realise that was a declarable claim - I did Google too to check that was legit and seems it's a common misconception. Probably worth insurers specifically asking about windscreen damage claims during quotation.
I had a windscreen replacement going back maybe about 8 years ago now, so probably out of reach to do anything about it. Will definitely bear in mind next time the potential costs of a claim vs paying out of my own pocket.
Come to think of it, I seem to recall not even speaking to my insurance company to arrange a repair, it was just a case of entering my reg into auto glass website and they did the rest.