You would be able to get that smooth, you leave it for 20/30 minutes so it firms up a bit, splash some water on it and use the float to smooth it, repeat this 2/3 times and it will be smooth.
Each time you use the float you will pick up some plaster on it which you can use to fill any low spots
Cheers. Just gave that a go, helped a bit. Some bits had gone off too much. It's all good. I started with the notion that it would all have to be stripped off, but as it stands I'm sure my RO sander and some filler will hide most of the nasties.
You would be able to get that smooth, you leave it for 20/30 minutes so it firms up a bit, splash some water on it and use the float to smooth it, repeat this 2/3 times and it will be smooth.
Each time you use the float you will pick up some plaster on it which you can use to fill any low spots