I've let many opportunities pass, in my past. Some have resurfaced, some have not. It is my goal in life, to live the rest of my life with no regrets.
Sometimes taking opportunities may involve, being prepared, in whichever way is needed. Then sometimes, you may never be totally prepared. Also, I've learned "being prepared" is different based on who you ask.
So why not just do it, just go, just be it. If it works out, how amazing. If it's not the place for you, you can always leave or go back home. If it's not you, then leave it alone and move on. Life is about continued growth, adventure, happiness and love. You can always be proud of yourself and say you did it. Which is way better than looking back saying, I wish I had....