Buying a 1st boat
We''re not quite in the same circumstances (no circumnavigation plans), but permit me to offer some advice. Do not rush things. You have four+ years to learn and research. What you think you want now will most likely be nothing like what you decide you want/need four years from now.
Hopefully, you can devote a large portion of your available free time for the next few years to reading and studying all sorts of info related to sailing and cruising. You will find that you may get 3 different opinions for every 2 sailors you ask; just keep an open mind and decide for yourself after you feel confident in your knowledge.
You should also definitely get some good basic instruction and get out on the water (charter, sailing club, etc.) soon. Actually buying a boat will be a potentially big financial commitment, so that''s the part we''re leaving until last. Before we do that, we''ll have as much education and experience as is possible to have without actually owning a boat.
Keep in mind that you won''t really know for sure that such a cruising life is for you until you are doing it. The more you can experience in the meantime, the better the odds that you''ll make the right decision for you.
Good luck in your planning.