There are virtually no true dull orange terracotta colours on the market as yet, surprising as Terracotta is all over instagram at the moment. You could go to Valspar and get one mixed. This is one from Graham and Brown... https://www.grahambrown.com/uk/sweet-potato-pie-matt-emulsion-2.5l/CT-090-017-107038.html?gclsrc=aw.ds&&sv_tax1=google&sv_tax2=Performance%20Max&sv_tax3=Performance%20Max%20-%20Paint&sv_tax4=CT-090-017-107038&sv_campaign_id=16443634521&gclid=Cj0KCQjwz7uRBhDRARIsAFqjulmkJMqNo8JOup1ClXTVOevb21DYEiP6V5k5T6QViYIYn7ummFXZjAEaAq9DEALw_wcB

It really depends on what colour and fabric you have in mind. You could go for orange but it's a bit obvious. Is it for winter or summer? Do you like wool or would you prefer cotton, linen or a blend? A deep green might work or a stony neutral. Budget wise there is so much choice it depends on how often you wish to replace it and whether quality is important. Ikea has some nice ones at the moment (seasonal) as does H&M and Marks and Spencer. I have summer and winter throws.

How on earth do you get out of that chair? No arms and low to the ground. It’s a no from me!

I assume the furniture in your pictures are not yours? I have a through lounge too, that is you have to walk through the lounge to get into the kitchen. It is what it is. I think put the sofa on the wall opposite the stairs, then tv on the stair wall or on a nice big tv stand. Ensure the tv stand is bigger than the tv if possible. People entering the lounge will walk across the tv area and that can’t be helped, but you need to measure the wall opposite the stairs accurately as you have limited width there. When I recently bought a new sofa I took measurements with me to ensure the sofa would fit comfortably. Never just assume it will fit. This is my sofa and door wall, the tv is opposite next to the fireplace.