I guess you could use it in titles of texts like "Pride & Prejudice", as sometimes they are distributed to the public named as such. Just don't use the symbol to replace the word "and" in the middle of your sentence eg. the word both reinforces the previous idea and suggests...
PS. But it doesn't take *that* longer to write "and" than "&", does it?
Now that's certainly something to go by... Standards package responses never seemed to represent answers that were actually good so that people like you don't just copy their style straight up.
Don't use & in essays, but they're not going to mark you down for it relax -_-.