You only need the free one.
As I mentioned a long time ago in questions about gps and my Garmin explore 2, two years ago when I went to Scotland, when I downloaded the western Europe or whatever it was Garmin free download, it said insufficient space, and I had to delete the existing North American stuff first---because of this I only did this closer to when I left so I could keep using my Garmin in Canada.
Unless I'm mistaken, or was mistaken at the time, you you most likely will encounter the same thing.
Let us know.
I actually forget when you are leaving, but it's very much in your best interests to keep using this GPS as much as possible to learn all the ins and outs