You are very lucky to get an appointment at such short notice.
i was struggling to get an appointment with any NCS office, but managerd to get an apointment in chester on my way to preston, the lady kindly re-arranged her diary to fit us in.
I have to say it it worht usig htis service, while it may cost you money, they ensure you have all teh corect documents, have comeplted the form fully and will give you back you original documents.
I applided on 24th feb, and gto a reply from the council 3 weeks later for citizenship ceremoney, however,m the Home office had written to me withing 2 weeks notifying of my application being accepted.