Excellent work on adding postcodes https://osm.mathmos.net/addresses/pc-stats/DE/ DE1, DE4, DE5, DE45 and DE72 should be showing 100% when the statistics are next refreshed. 
If possible please add addr:city for the relevant post town Derby, Matlock, Ripley, Bakewell etc.
Sometimes useful to add addr:suburb, addr:village or addr:town https://osm.mathmos.net/addresses/addr-tags.html although I have only ever used addr:town for Wirksworth (DE4 addr:city = Matlock)