'a 'n't she?
The magic word you're looking for is " inni' " (isn't it). This can also be used as a full stop, colon, semi-colon, while the word "yeah" takes the place of the comma.
That's only a south eastern thing (and a pretty modern one - old people usually use 'aint it'). Where I grew up it would have been 'a'n't she?
or (or possibly dunt she?
isn't used at all (the equivalent would be inti'
and you certainly can't use that in any place where isn't it
Of course, where I grew up you might well hear 'dunt tha?' (don't you) or 'sithee' (see you) as thee and thou are still used in everyday speech. There really is no such thing as an English accent so if (as in the post that sparked this topic) someone asks what would sound most natural to a native Englishman, my reply would have to be to ask, 'from where?'