伝えたいことは、
「はじめまして」
「ホームステイ楽しみにしてます」
「迷惑掛けてしまいますが、よろしくお願いします」
という様な感じです。

—-
Dear Mr.AAA family,

Hello all!

This is Hanako who is going to visit you from Apr.17th.

I’m looking forward to stay at your home !

In Japan, now it’s Spring, and warming day by day, so the cherry blossom
which is very famous in Japan is now in full bloom.

How about you in Canada, do you have particular stuff in Spring or the other season in Canada ?.

BTW, I’m not very good at speaking English, so sorry in advance, if I
make mistakes, and please correct me my English.

To be honest with you, it took about 2 hours to write this e-mail B^P

It’s first time for me to stay at overseas, so I might discommode you
sometime.. but please forgive me if I might do something wrong..

Again, I’m looking forward to see you in Canada!

Regards,
Hanako