After much researching about training and plans etc it was obvious that I needed a plan to follow to achieve this goal. At first I thought I could do without one but realistically without something to follow I would probably stray off and vastly undertrain.
After much browsing different plans I stumbled accross this plan http://www.trifuel.com/triathlon-training/Half-Ironman-Training.php
It looked pretty acheivable even if I changed it slightly to fit into my life. I play rugby Thursday evenings and Saturday afternoons, I did plan to give it up for the season as to risk of injury but I think the benefits of physical fitness and social benefits far outweight the injury risk.