Hi Martin and welcome aboard.
Did you purchase the 2015 FF from a dealer or private party? IF from a dealer, did they offer any warranty?
Personally, I've never purchased an extended warranty/service plan on any item as don't believe they are a good "investment." That is, if they weren't making a bundle on those extended plans, they wouldn't offer them.
However, to each their own so best in finding one that meets your expectations.