There is a TV program, about 10-12 episodes that aired this past winter on various public/knowledge networks called "Ocean Wanderer" It chronicles the adventures of a Canadian family that did what you are envisioning, taking about 7 years all told to do the trip.
Their story was not without obstacles and problems, and it's enlightening to see what types of things can spoil the best laid plans. (starting with the boat they bought)
Anyway, it does sound like you may not have the background or experience to tackle something like this so soon... If that is not true, apologies for that.
Do you have a boat now? what type of sailing have you done? These questions and more need to be addressed before you go further.