I have just become a british citizen after naturalisation and am looking to apply my wifes as a spouse of british citizen, but there is a tight squeeze due to booked travel just around the dates she becomes eligible:
She meets all other requirements but the residence which will be met end of this month as detailed below:
-> First came to UK as Tier1 Dependent, arrived in UK on 31st October 2010
-> Extension FLR(M) followed by ILR on 10th Feb 2013
Spouse (myself) gets citizenship in September 2013
-> Will complete 3 years on 30th October 2013
-> Plan to apply in NCS on 29th October 2013 such that application will reach home office on 30th October 2013 .
-> Travel out of UK booked for 3rd November 2013, i.e. the 5th day after applying at NCS.

