Hi Katie,
Welcome to the boards.
The training opportunities for a diving certificate are either agency or club. Which ever choice you make, your a winner. It is a pastime that has held my interest fom my teens and still does, now that I am in my fifties.
Many people I know, had their introduction to diving through a Padi open water course, on an adventure holiday.
I wanted to start scuba diving when I was twelve, but was only allowed to snorkel. These days most clubs will train 14 year olds.
If there is a scuba club in your area, it may be possible for you to have a free try dive in a swimming pool.
Scuba diving is a sport you need to be water fit for, which is one of the reasons I think people should dive regularly or not at all.
Regards,
Budgy