Welcome to Week 5 and we are starting with a mix workout - Yes it will be challenging on the lungs and legs but here we really want to work on that technic and maintain forming when you are under pressure and fatigued. So if I were you I would forget about the numbers, switch erg mode on and let them happen.
Lets concentrate on your breathing, your HR, your cadence, as well as having no dead spots in the pedal stroke, down through the ball of the foot and up through the knee is how I think of it.
So we are starting with a slow build, then jumping up to 3 sprints before we hit the meat of the workout with some workout in and around sweetspot (85%). Enjoy, forget the numbers and concentrate on the other equally as important aspects.