UK Standard Visitor Visa for EU family - Marriage Proof

Hi,

I am an Indian national, married to a Spanish national living in Spain. I am applying for UK standard visa (10 years) via the Madrid embassy.

As proof of marriage I am going to be submitting libro de familia (Spanish family book) in original,copy and translation.

I will also be submitting marriage certificate but only a copy and certified translation as my marriage certificate is with the Spanish authorities and to get a new one it has been delayed but this is the back up plan.

Question is will libro de familia be enough?

I can send the marriage certificate as soon as I have it but it depends on the Spanish authorities as its been holidays in Spain. Do you think they will let me send some docs later?

Please help me I have application soon.

p.s. I didnt applied for EEA family permit as it due to work I need to go to the UK