Citizen enter the UK on a foreign passport....

[razergd1]

We are currently in a trip abroad. We received an email the our child citizenship application got approved.

We have in the family 3 ILRs 1 child have a British passport and the youngest has a BRP (PBS dependent not expired but might be invalid at this stage) and we have the email he got citizenship including UKVI ref number.

The thing is that our postman tends to sign our post and drop it through the letters hatch... So most likely the certificate is already at home.

I don't think we will face issues boarding the flight as we are non-visa nationals, but are we going to face issues at the border? Or am I just overthinking... Should I try to use the BRP? Or print the approval email and show the border force?

TBH, I'm thinking of showing both.

[alterhase58]

Show the BRP only. Shouldn’t be an issue.
The thing to remember is that only the certificate confers citizenship. The approval advice is just an advice.

[razergd1]

The email also says that he do not need to attend a ceremony and he's a British citizen.

To be honest, reading again, the email says the BRP is invalid once we received the certificate... So hopefully the fact that the certificate is at home is not considered that we already received it... My understanding is that a minor starts to be a citizen at the date printed on the certificate.
I'll have a printout of the email just in case.

Thanks for the opinion! Much appreciated.

[meself2]

The email also says that he do not need to attend a ceremony and he's a British citizen.

To be honest, reading again, the email says the BRP is invalid once we received the certificate... So hopefully the fact that the certificate is at home is not considered that we already received it... My understanding is that a minor starts to be a citizen at the date printed on the certificate.
I'll have a printout of the email just in case.

Thanks for the opinion! Much appreciated.

If you can explain the situation at the border, you should be grand - nationals can't be denied entry.
Show BRP to the airline clerk (they don't have an option to figure out whether it's valid or not in the system) and explain what happened when you're in the UK.