What a beautiful room! do you or your partner play? Not sure the orientation, but its a good to protect working instruments away from strong heat/light sources, as it can affect tuning. Love the idea of playing, looking out to the garden. Have you considered a library/music room? Retain sofa; add a couple of comfortable armchairs (modern would work wonderfully - maybe linen tones ); use a white revolving library stand for music scores/general reading - won't interfere with the stunning panelling and stops the build up of music on the piano, which drives tuners nuts - and have a couple of well placed low/ small tables for drinks while listening/watching the fire, or both (this is good opportunity for a contemporary touch). I love round tables, because they are neutral to orientation (they don't suggest that you should be looking down to the piano or across to the fire place). If it is becoming too polite/traditional for you, use cushions to add zing and strength, and a larger/stronger piece of art above the fireplace (,maybe unframed - the white surround could act as the frame) and take down the candle sconce.
The floor boards are beautiful and rugs/carpets deaden acoustics, so I'd see how your piano sounded in the space before adding floor elements. If the space is a bit "live" or you just want to add a rug anyway, a modern pattern/ weave would add a contemporary element.

Float the loveseat perpendicular to the FP facing the end window. Float the piano on an angle opposite it with the lid opening back in the window direction so the sound escapes into the room. The pianist would sit with back to the FP, looking out both windows. Move the clock to your foyer. A pretty cocktail table for the sofa and a floor lamp near the piano is probably all you'll need other than an area rug.

Prior comments all contain great ideas! There are lots of lines in the room so I imagine some circular elements would soften this. A round ottoman with a serving tray might be an option. Much of what should be added to the room should enhance guests enjoyment of the music including some tables for beverages. And yes certainly have the piano angled so the keys show from the foyer. A fresh plant sitting on the floor might also be a welcomed addition.

Hi.....You say the only room available is the dining room, is the picture of the living room
and if so, draw a floor plan with dimensions. The way your showing the piano in the corner is wrong, the person playing should be facing the room, and the curved and beautiful side
should be facing the room. I'm assuming you want the piano in this room???

HI Matilda, yes the piano will be in this room, since we don't really need a formal dinning. We moved a few things around per some suggestions! And of course, we'll need to add some furniture and accessories! the dimensions are 11 ft. (wall perpendicular to FP) and 14 ft. (wall directly across from FP). Thank you so much for the input!

Hi......What is the dimension next to the fireplace to the window wall where the loveseat is?

46 inches, and I added a couple of shots from the other end of the room, facing foyer/kitchen.

Hi.......This is what I would suggest, it has the piano facing the room and the player facing his audience. I didn't have a template for you loveseat. and I don't know what other furniture
you have for the room, just keep the furniture out of the hallway. This is a charming room,
makes me think of a library/music room with the fireplace.

Hi Matilda, thank you so much! We don't want to crowd the room too much with furniture, so your suggestions seem to fit quite well. I'll work on it and keep you posted! Thanks again!