Had a read of your blog and firstly if world cruising is what you guys want to do then do it, there will be and will always be a whole cast of people that will give you reasons not to do it.... because there are and will always be a whole bunch more sensible, more acceptable things to do with your life than circumnavigate the planet at walking pace in a small boat. But that my friend is why they call it an adventure
Having said that and assuming you and your girlfriend are serious about this and its not just a nice little idea, realise that you need to develop a realistic plan in terms of gaining experience and knowledge, outfitting a suitable vessel, and last and certainly not least paying for the whole affair.....
I had a similar idea to you 6 years ago and im still getting ready, it may take you less time sure, but like anything worth doing realise its going to take a bunch of work and commitment.
For both inspiration and also for his practical advice, I would recommend the books "By way of the Wind' by Jim Moore and also its sequel 'Swan'. It is essentially the story of a guy who knew nothing about sailing coming home from work one day and announcing to his wife that he was going to build a boat and sail them around the world. If Jim had been on Sailnet at that point in time he would of gotten a bigger slamming on here than you!! However an infinitely practical fellow he did indeed build a boat, learn't what needed to be learn't about sailing and embarked on a successful circumnavigation. In turn he became a very experienced sailor, and has alot of good advice in his books for those looking to follow in his footsteps.
There are countless other tales out there that are similar about unlikely characters successfully doing what you want to do....often after being told that they couldn't or shouldn't. Read them all, read everything you can get your hands on, work out what works and what doesn't.
In terms of boats, you mentioned a Beneteau 42 in your blog, I would think long and hard about getting too interested in big pretty Beneteau's for what you want to do....I won't get into it here because there is ample discussion on this forum already, once again read it all and be informed.
Good luck. hope to see you out there one day, If i do the first beer is on me.