Hi there, few months ago I already posted this Topic and sorry for asking ur help again..I'm just got confused!

I am married to a British. I got already my ILR. mY problem is my Philippine passport will expired on May next year.
1. When is the right time to apply to renew my passport?
one of my friend said I can apply anytime. So I booked my work Anual Leave on March,so I'll be able to go to London Embassy...but my other friend just told me that I need to renew my passport 6 months before the expiration. Which of them is right? huh huh huh me confused! Helppppppppppppp.
2. I wish to use my husband surname in my passport,Is the Embassy will authomatic change it? any requirements?
tnx!