I'm a clyde and have done multiple half-Ironmans (HIM) and one full Ironman (IM). The step from Oly to HIM is not that big. My advice - train each event but focus on putting in the km on the bike for training. As a non-competitive swimmer, just get through the swim. Time-wise its the shortest portion of the event and losing 5-10min to the front runners in your age group won't kill you. Then you have 90km to make that up. Sounds like you can more than hold your own on the run. Good luck.