You can put the TV over the fireplace, not the best situation but the way the room lays out it is the only logical place to put it. If you could you should add one additional layer on your mantel that could extend it out another 4" to deflect the radiant coming from the fireplace. I would also mount it on a slimline mounting bracket and have the bottom of the TV no further than 4" above the mantle. Ideally you want the TV to be in as straight a line as possible with your eyes. You don't want to look up too high at the TV, it's like being at a sports bar. Also if you can snake up the power and the HDMI from the cable there is a box they make that has both in one so it makes for a very clean installation.

You could really use anything - I do support the no fire arms idea. Look at your hobbies e.g if you are into sailing maybe some Oars, cycling a brightly covered wheel rim, gardening an antique tool, antiques & collectables a brass beg warmer, music a gitar, violin or saxophone, or fishing rods etc if all else fails a massive traditional or highly decorative modern mirror which will throw the light around the room. Make it something that shows who you are & your personality. It must be a passion or somthing rhat brings you pleasure.

Not wanting to build anything just make this fireplace look nicer and not so much of an eye sore... cheap and DIY as it's a temporary house!

Needing ideas on how to make this fireplace more modern and inviting? Just at our temp house till we can sell it? I like modern/Scandinavian style. Clearly it needs a clean first! And we will be putting down new carpet.