Roger, if I were you I would not proceed in that way.
Here is the
webpage where IND gives instructions to its staff about photocopies. Whilst 1.1 sounds very negative, 1.2 is much more positive, given that I suggest you do get a Solicitor-certified copy.
So if you really do need your passport for travel shortly after your naturalisation application is submitted, just get a certified copy of the passport and submit that instead.
That is, go to a Solicitor and say you need a certified copy of your passport. But do note, for naturalisation applications, it is essential that
every page of the passport is copied ... even the blank pages! A fee will be payable.
Then armed with your certified copy passport, submit the naturalisation application by post .... and of course post it no later than Friday 28th October is you want to beat the new test requirement. And given the importance of the application and the documents being enclosed, do use
Special Delivery to post the application.