I think that I will trial this a little and start off simply by halving my best 400m time and running both 200m at this time. I will have 2 minutes rest between the 200m reps to start with and 20 minutes between sets. With each session I will reduce the rest between the 200m reps and see where it goes. I am hoping the first session will not be hard so I will have alot of room for improvement and don’t burn out. I would like to get down to 30 second rest between reps and then test the 400m.