The reply above got it right. I was wondering the same so I called KCC and this is what they told me: KCC will not send a confirmation of receipt email (unless you had sent your docs by email). If you want further proof that they got it--since in your case you already know by virtue of your registered mail--you can call them and they will look you up. Best of luck!
. . . as for the police check, I suggest you get on it right away because your number is extremely low, thus you will most certainly be called for an interview in October.