I was wondering if the 'subjonctif' is used often nowadays? When I learnt it at school, my teacher said that you can't speak French without it. Is this actually true?
Subjonctif is absolutely required to correctly express basic things such as doubt, duty, hypotheticals, etc.
Some tenses of subjonctif (specifically the past tenses) are currently no longer used as much as they used to outside of the literary context.