bokeh1.8 (do you shoot with prime lenses??

),
your just do it attitude is good, but you don't have to offer free services to attract people to allow you to learn and gain a portfolio.
in the best case scenario, all is good and all the parties are happy. the couple might think you are so good, they tell their friends you are good and should be charging $$$.
in the worst case scenario - well, let's just say that even if you are offering free services, there might be couples who might have unreasonable expectations.
as suggested by other forummers, you could look for a willing mentor and do some shoots as a second photog.
my very first few weddings done close to a decade ago were no-fee affairs for relatives - ok, they still gave me angbows. I even didn't use my own camera - i borrowed a single camera and hammerhead flash and learnt about 1/40 f5.6 bounce flash from my school mate.
then i did second photography for about two years on and off for friends and strangers (advertising at singaporebrides, which Kuang suggested) whenever the opp arise, to build a photojournalistic wedding portfolio.
i would say you will have much more fun doing second photography to a main photog. will pros take you in? i'm sure some are happy to mentor you.