For the cushions you've chosen, I would buy modern sofa with clean lines in gray colour. The best place for sofa is the wall opposite the chimney breast and you can build the shelves on each side like on one of the pictures. Smaller sofa or two armchairs can be placed against the wall opposite the window. I would open the fire place and place there some wood blocks.

Thanks Minnie and Gary. That sketch is fine. You've both suggested TV in the same place and build round that area. And that's where I was thinking of putting it too. The separate area behind the sofa adjacent to the fireplace looks inevitable, you've both suggested that. Which isn't a problem. I guess it's just too big of a room to try and make one space, everything would be too far apart. Just need to make sure I think carefully what that space will be used for so I don't waste it. Kids already have their own playroom so will be keeping it for the grownups!

I’ve tried to edit the post to show the specific room in question on the layout but there doesn’t seem to be this option!

Hi K S, narrow living rooms can be tricky with the layout, we've helped many customers with similar room shape and size to yours. We have actually written a blog sharing tips for rectangular living rooms, I have linked this below. https://www.thelivinghouse.co.uk/blog-interior-design-tips/how-to-design-your-rectangular-living-room You may also find our Facebook group community helpful, its another place to ask questions and gain free advice from like minded interior lovers and us as experts! Here is the link if you would like to join - https://www.facebook.com/groups/interiorhomedesignadviceandsupportuk