You've got a year to prepare, and an aggressive, ambitious and focused goal is not a bad thing. But what you need is experience, experience, experience.
My advice to you would be to crew as much as possible on passages as long as possible, including at least one Biscay crossing. Get some skippering experience - especially in entering unfamiliar ports by day and night. Do the Yachtmaster theory course over the winter and read as much as you can about extended cruising and especially about heavy weather sailing (I'd recommend Fastnet Force 10 and a book about the Hobart's disaster). And pick your crew carefully - have as much experience onboard as possible.
Of course, in order to rent a boat you'll probably need a certain level of qualifiations in order to rent a boat - and the ICC propably won't cut it. That likely means getting 1,500 miles under your belt and doing the Coastal Skipper exam at least.
You're not naive thinking you can do this in the next year, but you've got a lot of study, training and, most importantly, seatime ahead of you if you want to make it happen (responsibly at least).
Bottom
line: Setting ambitious and challenging goals is good. Being stupid is bad.