I am an amateur lover of home decorating. I too have a very awkward long narrow living room that is 350cm by 620cm. Additionally it has diagonal traffic flow from the front entry to the rest of the flat. The owners have built a cabinet at one end for the TV, etc. I think I would make a cosy seating area at one end of your long living room. Place a grey or brown sofa at one end but not against the wall. I like the idea of a narrow console table behind the sofa with a table lamp, a plant or a large statue. This brings the end wall closer in. A peachy or raspberry carpet in front of the sofa will pick up the wall colour and anchor this seating area. (grey and some browns also coordinate with raspberry/peach). A couple of raspberry sofa cushions can help include the wall colour into your overall scheme. Single chairs opposite the sofa allows visual and actual flow down the narrow room and completes this seating area. At the other end of the long narrow living room I would place a reading chair, a floor lamp and a small round coffee table. If there is room you could have a tall bookshelf with you favourite books. What do you have on the long side walls? I have windows and doorways on both long sides. I decided to use pull up shades on the windows instead of curtains which I thought would make my narrow living room look more narrow. The wall colour is white but I think I will tone it down to a soft grey. I plan to paint the end walls a darker grey.

Too many colors and dark colors make the space smaller also in your decor replace the printed cushion with a lighter shade of same blue. A small floral painting behind the sofa beside the window having rust,blue and cream on it will look good.Side tables on sides of the sofa should be there. Side tables of U shape whose Base can slide below the sofa side are available in market they will look great with your decor. You can put a small matching square table between the corner made by the handles of the sofa and put a small plant like mini bamboo on it. I hope my suggestions are of some use to you thanks

that is what i have added if you can see the pic above.. want some suggestions on partition that i can use between dining and sitting

Its just really messy right now. Too many colours and clashing prints. Is that Puja unit lime green? Or does it just appear that way because of lighting? Either way, it stands out like one more distraction. Pick one base colour add and add prints that go with that base. That TV unit HAS to go. So do that black metal coffee table and the carpet. I would suggest you go with a simple geometric print in the carpet. But apart from these obvious design gaffes, the structure has distinct possibilities, if you do a classic English style. The railing above adds some interest