A belated welcome to the forum.
I BELIEVE it's easier if you opt for a civil ceremony, because the original marriage certificate is then passed directly up the line for NSO verification in Manila ... whereas, the Catholic Church has a tendency to allow certificates from several weddings to pile-up before passing them over - in bulk - to local Municipal Registrars.But this is only MY opinion.
As regards a spouse being interviewed by the British Embassy, I think it would be safe to say that this is only likely to happen IF, the Entry Clearance Officer assigned to a case, is not fully satisfied with all - or any relevant part - of the evidence submitted by an applicant.
And finally, it's difficult to guage how long it will take to assess either of the two types of visa application you've mentioned - although, there has been a recent trend towards a speedier outcome.
Hope this helps!