Pic/step # 5 above shows the lower turbo heat shield bolts that need to be removed while under the car.
Pic/step #16 shows all heat shields removed to unbolt the downpipe from the turbo.
Pic/step #20 shows the DP removed to undo the turbo bolts from above.
Only the 14mm uppipe support bracket bolts have a nut on the bottom. That can be accessed with a spanner from above the car, once the heat shields and downpipe have been removed completely: