My first reaction is 'what odd beams'. Odd isn't always bad though and can add a lot of character, how about painting it all white including the ceiling and the shelving. It's a lot of work but it would brighten it and neutralise everything. Modern to me is all about white. I like your shelves and I think you could get some really awesome objects to display on these as features. Good luck!

Hi Rosie, I would start by getting rid of all the existing ornaments. I would then put two pictures in frames on the top two shelves. I would lean them back against the wall rather than use a stand. I would then add an ornament either side. Perhaps something glass or mirrored to create some light and interest. I would then buy a couple or lovely big log baskets and put them either side of the log burner make more of a feature of it. This will then draw the eye to the log burner rather than the fireplace. Hope this helps!

Regarding the fireplace, what type of fire are you thinking of having? If its a real wood fire of gas fire, then you may need to take into account a chimney/flue system. It looks like both options you have suggested have the fireplace in the original house and not in the planned extension, which means any flue/chimney would likely need to to run up through the house and may cause issues with the space above. There are some great options available when it comes to fires and stoves that might allow you to position the stove away from the wall and perhaps more central in the room. Double sided stoves with glass on opposite sides are good options when you have bi-folding doors as you can enjoy the ambience of the fire from both inside or outside.

The pipe in the marble one may be a gas pipe where someone may have had a gas fire inserted there. If it is, then a gas engineer will be able to remove it and seal the end for you. It may be an idea to get all the chimneys swept before you decide to use them for a fire.