You will need to book an appointment with HMPO if you want to apply for a BN(O) passport in person at a passport office.
In person passport applications in the UK is more expensive then postal applications. For a standard 32 page British passport -
One day premium service - £128
One week fast track service - £103
Post Office Check & Send service - £82.25
Postal applications - £72.50
要去London整 - There are also a number of regional passport offices that you can go to for urgent passport applications. As far as I can remember, there are regional passport offices in Belfast, Durham, Glasgow, Liverpool, Newport and Peterborough.