Online application question...

Hey all,
Hope that someone might be able to help me out.
I am currently living in London on a Working Holiday Maker visa but now applying for ancestry visa as my grandma was born here. I am going home for the summer in order to do biometrics etc. but was wondering if anyone knew if I could send in the online application and book the appt while I am still over here in london??

Thanks so much,
Megs