How to Taken King question

This may have been posted before. I've looked but couldn't find anything about my question so I do apologize if it's been asked many times.

I would like to purchase the Taken King but I never purchased the first two expansions. I'm assuming my only option for the Taken King is the disc with all the first two expansions and the taken king on it?

Also, if I buy the disk, how do I get to keep my character?

Just confused at how it all works. Thank you.