You are lucky being able to do the online application - in my case it is impossible, I have to make an appointment at the UK embassy, who then physically tranfer all the papers to the UK, which makes things slower and more unpredictable. I have in fact finally decided to get the new passport by returning to the UK, using the one day service.

It seems crazy to me that there is no fast track service for people living outside the UK, who logically need this service most under the new system.