Hi!

I am an Australian and am travelling to the UK for two years on a visa at the start of next year. While I am there I am wanting to apply for my Spanish Citizenship. My father was born in Spain and my grandparents so I am eligible for a citizenship by origin. My questions are,

1.) How long would it take for me to receive the passport?
2.) My father doesn't have his birth certificate, he was born in Gijon, Asturias, would I need to go to the civil registry in Gijon to get it and would I be able to obtain it?
3.) If I can get his birth certificate, what documents do I need to give when I opt for the Spanish nationality? E.g. my birth certificate, his birth certificate?

Thanks!