A modern equivalent for "at the coalface"

Solution 1:

Perhaps in the trenches. In the context of medicine (but it can be applied to any field that has active practitioners as well as academics and commentators) it has been defined as

A popular phrase derived from trench warfare of World War I, referring to the active practice of medicine—in the 'real' world—as opposed to the less practical philosophies of the 'academic' world

Segen's Medical Dictionary

But given you request for a more modern idiom, this may be a bit esoteric (and perhaps not understood by generations unfamiliar with World War I).

Solution 2:

You've got a range of choices;

• I haven't been on the front-lines

• I haven't been hands on

• I haven't been involved with the nuts and bolts

• I haven't been involved with the nitty-gritty

• I haven't been involved with the day-to-day operations (or even just "the day-to-day").

That said, 'at the coal-face' would be perfectly acceptable and explicable to most English speakers.

Wiktionary offers some additional alternatives.

Solution 3:

I'd go with this:

I haven't got/gotten my hands dirty in years.

Solution 4:

My great-grandparents were of mining stock, but fortunately I don't have to work underground. I'm a software developer and often speak about 'working at the code-face'.