Travelling after Approval British Citizenship

Dear Members, I am wondering if someone can help me. I applied naturalization for my 15 old son MN1 which was approved yesterday still waiting for certificate to receive via post. My question is we already booked tickets, hotels and transportation 2 weeks ago and traveling on 10th august to Saudi for Umrah as we do not enough time to apply his british passport. can he still travel with his Pakistani Passport? The approval email which I received yesterday saying after receiving naturalization certificate ILR/BRP got invalid. can someone please help me how to deal with this situation. can I carry original certificate along with Pakistani passport as travel documents or that's not safe idea mean on return have to face immigration with a lot problems.

As your son is a minor he can apply for an expedited British passport. Suggest you get the passport sorted quickly as once the certificate is received he is officially British so he doesn't have a legal immigration status.

I just checked but there is no way to apply urgent passport on 1st passport, urgent passport service only available on renewals. Can anyone suggest me what should I do in this situation. Thanks

For children there is a 1 week fast track service for a first passport.

Thank you, I submitted application today hopefully will get before 8th Aug.