So I did my first set of 2km today.
My target was 5:50 per Km
Lap 1 - 10:28 - 5:14/Km - AvHr 155
Lap 2 - 10:54 - 5:27/km - AvHr 160
Lap 3 - 11:14 - 5:37/km - AvHr 162
I forgot to read the rest period before I left the house so I just took 60 seconds. Just checked it again and realised it was 90-120. I'll have to be more careful to double check in the future!
I found this reasonably comfortable, I wasn't busting myself although I found that on km 4 I was slowing, but with the break I was then able to keep that kind of pace for the last set which was still okay.
Is there any more info you require from me in terms of averages etc?