fill hole

Hi, Can anyone help with how to fill in this hole? It used to be a gas fireplace but it's been removed. The flue has been taken down below roofline and tiled over. What's the best way we can fill and plaster so it's flush with the rest of the wall? And do we need an air vent seeing as the...

Hi all, I've recently had a new kitchen extractor fan fitted as the last one was ancient. However the fan was too small for the hole and had to be fitted to one side, leaving a large gap on the other. What would be the best way to fill this gap? The person who fitted recommended filling...