dia daoibh, I seem to be coming across alot of Northy words in my reading of late, for "chan fhuil" would one say (roughly) "chan-il ?

'maith agaibh

I think that's the case, although I can't remember for certain how I heard it in Donegal. In Scottish Gaelic, it's written chan eil, with the silent "fh" combination not even being written (though it was probably written years ago).

_________________
I'm not a native (or entirely fluent) speaker, so be sure to wait for confirmations/corrections, especially for tattoos.

It is sometimes used in Donegal, it's less common but more emphasized than "níl".
It's pronounced "ha-nil", but unlike Scottish Gaelic, the n is broad (in Scottish it's slender: kha-nyel or kha-nyahl)

_________________
Is fearr Gaeilg na Gaeltaċta ná Gaeilg ar biṫ eile
Agus is í Gaeilg Ġaoṫ Doḃair is binne