You can *just* do it without removing the dashboard (I have), if you drop the fusebox and remove the screws securing the lower part of the dash to the door pillar and to the heater/centre console, so it can flex outwards slightly.
Then you can get to the Philips screws with a combination of short and long screwdrivers. It's quite easy to feel where the holes (and screws) are, as they are deeply recessed.
But thinking about it, to do it properly the instrument surround should come off (it sits on top of the padded roll), and the screws for that are really difficult to get to (going up from underneath).
So on the whole, I go along with Chas and suggest you take the whole lot out (the heater can stay in place and the panel/knobs etc. can stay on the heater).
The hardest thing about getting the dash out is the disengaging of the hooks near the windscreen. It either comes out really easily, or it puts up a solid fight ending in the breaking of the steel clips (not the plastic hook!)
Re-trimming the dash roll is one of the best things to do to the Uno in my opinion - the NZ sun means most are ripped apart by now and it really lowers the tone of the car. From there it's a short step to ripped seats, mouldy carpet, a few big dents, and then you're driving a wreck. Not that some people mind that, of course
Strangely, the early 70S seems to have a better material (grey) that doesn't fall apart and still looks great - is that your experience rawill?
-Alex