Requesting the original non-British passport back from HMPO

Hi there,

Here is my timeline:

Citizenship ceremony: 27/10/2018
Passport application: 27/10/2018 (online+special delivery)
Passport application type: first adult British passport post-naturalisation; no name changes
Received by HMPO: 30/10/2018 (signature for the special delivery tracking)
Online status updated to "Declaration form received, being processed": 31/10/2018
Current application status as per the Passport Advice Line: going through the examination
Need to travel on: 11/11/2018

So, here is the question:

I need a passport by Sun 11 Nov because I need to travel. Thinking about requesting my original non-British passport back from the HMPO via a special delivery letter with enclosed pre-paid self-addressed special delivery envelope but I am concerned that:

(a) this may put my current British passport application on hold or delay it
(b) the HMPO may ask me to post my original non-British passport back to them again after travel and I don't want to do this because I don't want to be outside the UK without any passport

Please advise. Should I go ahead and request my original non-British passport back from the HMPO and don't worry about the above 2 points or should I miss the trip on Sunday with significant negative repercussions at work? Or do you think there is a reasonable chance I may receive my non-British/British passport before Sun 11 Nov?