Originally Posted by
continentalclub
As long as the reservation can be ticketed (not all ITA itineraries can be) then there should be no issue whatsoever.
The only odd instance is where a fare has a specific residency requirement, but these are not all that common, and wouldn't apply for a GIG-LHR ticket.
If I brush up on my Portuguese I can purchase from the TAM website. However it is all internal flights - not to LHR. The CPF number is optional but know this can be an issue so may be a reason for the price.