Simple way to block a fireplace?

[Will1977]

Hi all

my house was built in 2002, it had a fireplace hole, thing with wood and marble surround.
I then placed a fireplace to block the hole, it's never used, just mainly for decorative.

Roll on 2023, I want to build a media wall, which means the fireplace needs to be removed.

I looked at what people recommend, and most of it mentions a chimney cowl, and an air brick fitted when bricking it up.

So my question is this, as the media wall design is very simple, timber, plaster/mdf boards etc,. Can I get away with removing the whole fireplace and just stacking some bricks, not concreted in and leaving a brick or 2 out. Maybe add a chimney balloon? Or even just not bricking it up at all.

Or, what other options do I have?

 

[Wayners]

Just get a few thermalite blocks. Cut with old wood saw or buy cheap saw and use that.
Bag of dry readymade cement from DIY which you just add water. Chuck them in best you can.
Put small vent over to Keep mice ect out and airflow through.
Build your media wall