Green’s Dictionary of Slang

natch n.

also natcher
[abbr./pron. SE natural]

1. one’s natural life.

[UK]Binstead & Wells A Pink ’Un and a Pelican 180: You couldn’t miss ’im in yer natch.
[Aus]Sun. Times (Perth) 5 Nov. 4/7: The first time he had been away from Coolaballing in his ‘natch’.
[UK]Marvel 12 Nov. 7: Never in my natch, guv’nor.
[Ire]J. Morrow Confessions of Proinsias O’Toole 95: Now look you here, I niver took Prod money in my natcher!

2. see natural n. (6)

In phrases

on the natch

(drugs) not using any drugs or other stimulants.

[US]R.R. Lingeman Drugs from A to Z (1970) 190: on the natch [...] Not using drugs; leading a natural life as opposed to a life centred around chemicals.
[US]E.E. Landy Underground Dict. (1972) 141: on the natch [...] 1. Get off a drug without taking another drug to ease the pain. 2. Do something without aid or assistance.
[US]H. Selby Jr Requiem for a Dream (1987) 62: You have enough dexies to keep us working? You know we aint about to make it on the natch.
[US]J. Stahl OG Dad 228: I’m not closing in on death because there’s Mexican tar in my arm, it’s happening on the natch. You know, the cycle of life.