Shouldn't be a write off. New rear lamp assembly and a bit of paint, the bumper doesn't look damaged at all, that'll be removed for the bodywork repair and refitted. You should be able to just clip the bumper back on for now, align it and push. The rear lamp lenses may not 100 match after repair due to the new one compared to the old one. If so, I'd think a headlamp polishing kit used on the old one should make a difference. Things happen, such is life, this is why we pay for comprehensive insurance. Don't be hard on yourself.