I agree with my friend Giu on this.
If you really want to go circle the globs, go for it. But there are a LOT of issues in doing so. First, most solid passagemaking boats that are cabable of doing that are quite expensive. You can get cheaper ones (around 100k or so), but they will very likely need a lot of refitting to the tune of tens of thousands. You can basically forget taking out a loan for the boat. Cash only... since you will need insurance and it is very hard for lifetime sailors to get insurance to circum. Newbies can just about forget it. No insurance=no boat loan.
Also, the type of boat that is req for crossing the pond is traditionally not as wide and comfortable as a boat that is intended to cruise these waters of N/S America.
THere is more to see here than you can see in a lifetime. I am not trying to dissuade your dream, but I am giving some realistic advice... and this only is the tip of the iceberg.
What do you sail? I see it says Catalina 400 technical something at the end of your post. Is that what you sail? Cause if thats what you chose to spend all that money on, then you can not possibly know much about passage making.