Sending documents to HO Pre-emptively

[Joomla]

Wishing everyone a Great day

- I applied for British Naturalization on 12th Sept 2016

- I used NCS service in Harrow

- Some documents were missing ie Marriage certificate as it had been sent for my sons naturalization application, I have now received my marriage certificate back.

- I have received a confirmation letter of naturalization application received at HO with a reference number

I wanted to ask you knowledgeable guys

Question 1: Is it OK to send my marriage certificate to the HO, before they ask for it?

Question 2: Is it also OK to send any other documents like P60's preemptively which I couldn't send before?

Question 3: if its OK to send documents preemptively, what information should I include in the covering letter like reference numbers or others so that they put these documents by my my file and that they are not lost?

Appreciate your responses!