Supporting documents after passport delivery

Thanks very much for looking at my question.

We have recently applied passport for our child, which is successfully delivered.

However, the supporting documents is still not delivered.

I am wondering how the supporting documents tracking information will be available? Will Passport Office sends me an email for that? Or should I just search TNT website with post code and PEX number and there will be a second tracking with Freight Type supporting document with the same post code and PEX number?

Thank you very much for your kind help!

My supporting documents arrived Tuesday, just over week after receiving my passport.
I paid for the secure delivery. I didn't get any email from the passport office saying the documents were being sent but I got one from TNT on the morning of delivery.
You can track it using the same PEX number on the TNT site.. once the documents have been dispatched a new link will appear