How difficult are very thin render repairs?...

Dear Folks,

Without the hoped-for deluge of recommendations that I was planning to get in response to my previous thread about good Solid Plasterers to do some internal patch-up work on Brisbane's northside , I might have to have a go at doing the darn thing myself...

The Shower Recess render has been removed all the way back down to the brick. Getting some cement back onto this doesn't worry me too much because I will have a good decent thickness to work with.

Rather, what's got me worried are the bits where I haven't gone all the way back down to the brick, because I only used the Grinder instead of the Hammer-Chisel. Such will be the case in quite a few patches throughout the Living Areas of the unit where I have ground out the render by just a couple of millimetres over a width of a foot or so in order to remove some surface imperfections and badly repaired cracks.

I'm really sceptical about being able to successfully trowel such a thin coating of cement render across these parts. The coating will have to taper from just 3 or 4mm deep in the centre of each patch, back to effectively zero around the edges where it obviously has to mate back in with the existing wall surfaces. The walls have a slightly rough (as in sandy) texture in their finish.

From my very limited previous experience with render-repairing, once you mix sand into the cement slurry, the whole "feel" of the mix seems to change from something that was thin and sticky (like grout), to something that becomes more crumbly, and nowhere near as sticky. If you add water to stop the crumbliness, it becomes runny. And if you try not putting sand into it at all in order to keep it sticky, it loses any texture, and can end up sticking to the trowel like Sheep Dip...

I guess the long and the short of it is that I'm trying to use cement in skim-coat thicknesses, but also wanting a sandy texture in the final dried surface. People usually do these sorts of thin repairs with Spakfilla, but I'm not going to get any sandy texture if I go that way (unless I mix in some sand with it...) Can it be done with cement? Or should I try mixing sand into some Spakfilla? Anyone have any tips or warnings? Naysayers welcome . I might drive down there tomorrow morning and take a couple of photos (the traffic is too heavy at the moment; later on when it thins out, it will be far too cold...)

Many Thanks,
Batpig.