Green’s Dictionary of Slang

(UK black) to leave, to go.

1999		(con. 1979–80) A. Wheatle Brixton Rock (2004) 76: I have to dally now, so laters.
2001		(con. 1981) A. Wheatle East of Acre Lane 20: I have to dally soon and link up wid Coffin Head.