Yes, use them, just add some modern elements to counteract them. Walls must change, and bring in metallic, maybe bronze or brushed brass in a coffee table, it works well to make nostalgia into luxe. The curtains work ok here, just update their hanging system. If those mustard chairs are grannies, I wish I had that gran. The blue is perfect with mustard, and vibrant enough to detract and contrast the mint green carpet. I would definately select a colour in that rug, perhaps I can see a slight coral red, then I would introduce varying shadesof this diluted down into pastel tones. This will comp,ement the mint and subtly introduce more depth of colour which will overtake the institution green. Paint your walls absolutely. Not beige. I would go with a Chocolate colour, I think the richness would work with that lounge suite and also MInt green and chocolate are friends. Chocolate is also complementary to stones, beiges, creams and coffees, so whatever direction your kitchen eventually goes, chocolate will work. And if not, it's only paint. To make it livable now and still have some sort of positive edge about it, I'd try risky colours and textures, ones that work but ones you probably wouldn't even think of unless you had a mint green carpet. You could always rip up the carpet and see what lies beneath. Maybe there's timber there, or concrete. Either are a bonus.

I love your view! There's options here, and they'll be led by where your blinds are installed in my opinion. It looks like you might need to install the blinds to the face of the architraves, in which case, I'd be selecting pale blinds to sit outside the window as they'll, hopefully be up out of the way most of the time. If they fit inside the recess, then I'd select dark.

What is in the second photo, a power point? And you think the tv socket is going to be in that same wall? Then that is where the entertainment unit goes. Is that the only power point? When you buy your entertainment unit choose something which allows access for plugging in the vacuum cleaner. Unless you have a rechargeable vac which doesn't need a power point. With hard flooring perhaps you will mop more than vac. Although if you want to soften or warm the space you might have a rug? I didn't understand "combination of bright and neutral colours" until I looked at your Idea Book. You have some lovely pictures there. Do you have any artworks yet? That might influence which colours you repeat throughout your space. The grey sofas are probably the most versatile and timeless, and something like that might be the easiest to source in a size and configuration to suit your needs.

Lovely room,by adding art to your walls, a large feature rug, fabulous lighting and a beautiful centrepiece for your table and it will look gorgeous, I don’t think it will look dark.