Passport application after naturalisation

[Pulcina89]

Today I have attented my citizenship ceremony and because I applied via NCS apparently I was unable to apply for the passport at the same time as my citizenship application.
I went online to apply for my new passport and is requesting me to send the certificate of naturalisation and passport plus pay £5 to get documents back through secure post.
So my question is, what is the difference between applying online and via the Post Office “Check and Send” service.
Yes it costs £10 more, but it works out to be the same, by the time I pay for secure post to send documents required and get them back.
Via the Post Office I am assuming that documents get verified there and then and there won’t be any need of sending them to HO?!
I am just trying to understand what is the easiest and simplest way of doing this.
TIA

[secret.simon]

For all passport applications, the documents will need to be sent away to the Passport Office.

All that the Passport Check & Send service does is that the person at the Post Office (who is not trained by the Passport Office, but by other Post Office staff) casts a glance over your documentation and flags it up to you if you have missed any documentation out (such as if the photographs are the wrong dimension or you have missed out a field in the form). The documents will then be put into an envelope and posted to the Passport Office as usual.

[Pulcina89]

Thank you for the clarification.

Another issue that I have is that the field for "town of birth" which needs to match the name on the certificate, has a limit to characters that can be entered and I can't fit the whole name in it.

I am short of a letter, so how can solve this issue is there a place that I can add the correct info or should i send a cover letter explaining the mismatch?

Thank you again