- I want to resign from my Job when my baby is born and use last month of maternity leave as my notice period as well.
Company policy might not allow for use of maternity leave as notice period. And it doesn't leave a good impression.
It will probably be better to make it clear before you start maternity leave that you won't be returning (there's usually nothing preventing you from giving more than the minimum notice). There are legal protections for your maternity leave if you meet the criteria.
Apply for a dependent visa now - it's not that difficult and will save the guessing.