Someone can help me correcting this short introduction?

Well, the Australian ambassador will offer a cocktail here in Brazilia to students who want to study in Australia. For that, I have to send a short introduction of me, explaining why do I want to study there etc.
So, if someone could read it and correct it, I would be glad :)

I have never been in Australia, but I though about it when I was planning to finish my high school in another country other than Brazil—which did not even happened. I finished my studies here and started studying International Relations at Universidade de Brasília (University of Brasilia). This opportunity to study in Australia is unique, and a possibility to improve my English skills and to know more thoroughly the culture and education system of your prestigious country.

Someone can help me correcting this short introduction?

Well, the Australian ambassador will offer a cocktail here in Brazilia to students who want to study in Australia. For that, I have to send a short introduction of me, why do I want to study there etc.
So, if someone could read it and correct it, I would be glad :)

I have never been in Australia, but I thought about it when I was planning to finish my high school in another country unless Brazil - what did not even happened. I choose finish my studies here and started study International Relations in Universidade de Brasília (University of Brasilia). So that, this opportunity to study in Australia seems to be unique, and a possibility to improve my English skills and to know in a better way the culture and education of a country that is an excellence of it.

I'm not going to correct the whole thing because Andrés has made the needed corrections except he forgot to put the t   on the end of thought.