You sound like a lovely Mum someguy and if you are as close and open as you say then your son would no doubt approach you if he feels inclined to. In the meantime, as the others have said, leave well alone. It is something that boys generally find their way through on their own.
Sex Ed and PHSE at schools these days is quite different to the basic mechanics that most of us older generation were taught at school. They cover a wide range of the physical, emotional and consequential issues these days, along with educating about the issues surrounding drugs and alcohol too. I know, I am a school Biology Technician and prepare these lessons. Your Son will become better equipped to deal with these things than we ever were.
So don't worry too much about this stage of his life, just be there if and when he needs you.