My bike is around 50 lbs. I weight about 150 lbs. I often carry a bag about 20 lbs. So all in, it's about 200 lbs or ~90KG. I think my battery pack can go about 50 miles per charge, but I never went that far on a single charge. I usually charge after 30 miles to ease strain on battery, but that should still be plenty for you to get to work and back.
I can comment on the range. I have a similar bike with a 540Wh battery. Total weight close to 20 kg, maximum practical range approx 30-40 km. Slightly less when sub zero C temp.
Edit: I would consider an extra charger and charge at work for that range, in case you want to stop by somewhere on your way to or back from work.
I get 40km out of a 400Wh battery with similar weight.
About half in cold weather with snow and studded tires. The tires seem to be the main reason for the reduced mileage. This is in sport mode with maximum assistance and going full speed.
Hows the battery holding if you carry extra weight? How much does the total setup, you included, weights?