Talk idly (6)
(Other definitions for natter that I've seen before include "Chat casually" , "Talk continually or annoyingly" , "Chew the fat, shoot the breeze" , "Talk socially without exchanging too much information" , "Talk inconsequentially" .)
(Other definitions for tattle that I've seen before include "Tell tales" , "'Gossip, idle talk (6)'" , "Divulge secrets" , "Gossip, idle chatter" , "Chatter idly" .)