Love the enthusiasm! The club offers a lot of resources for exactly this kind of question. If you loved the New Triathlete Program then you might want to consider doing the Half Ironman Program that the club offers. As a part of this program you get access to a coach, a training plan, online forums, workshops, and much more. I personally did the program a couple of years ago and got a lot out of it. The program normally starts early in the new year so the timing of your question is perfect. Check it out at https://www.dctriclub.org/programs/half-ironman-program/. Let me know if you have any other questions. We are happy to help!
All my best,