Have you fitted the blinds yet? Would be great to see the final result!

I think Blues are beautiful, and can create some really dramatic effects using just paint, colours on cupboards etc. I wouldn't worry about the natural light, if it's as bad as you say ( and we have a similar problem, you're going to have to think about artificial lighting as well. Therefore, under-counter, pendants over-head, plynth lighting etc. The type of bulb and colour of bulb can be controlled to give you anything from daylight white to warm whites, so make sure you get the lighting right and choose whatever colour you like, after all ,, kitchens are top ticket items and you usually have to live with them for a long time! Depending on the type of house, you may even have the possibility to add a light tunnel, they're fabulous!

Roof light over Dining table - as you need good task lighting over your cabinets and worktops - which can be tricky to span over a roof light - people at table can look up to the starry sky or sit bathed in sunshine ! ( if it's a nice day !) and eat by candlelight !!!

Can you post a floor plan? It doesn't matter if it is hand-drawn - just something to give us an idea of what might work. I have two main comments. First, a north facing room is never going to look bright and light so, as many interior designers recommend, go with dark - paint it a warm dark colour on all four walls; go for a colour that works well with the fireplace, a contrast rather than a match. Secondly, I feel the sofas are too big for the room. I know you want to keep them but the room would have a completely different feel if you had slender, more modern, sofas with legs that are visible (which creates a sense of space) and I'd put them facing each other as whizzywig suggests. The coffee table would look good between them - it would look even better if it were rectangular and in a style that complements the sofas. You might then find that the display cabinet works better; its colour and style might blend in more if the walls flatter it. And you wouldn't need the side tables. The carpet might work, too, if the walls were darker. I agree about the ceiling - it needs a skim; paint it in a softer, lighter version of the wall colour. I'd also remove the ceiling light and have more table lamps to give the room a softer, warmer feel. It's probably hard to move the television (does it need to be there to be near a TV point or is there one on the other side?) but it is dominating the room (it should be less obvious if you paint the room a warmer, darker colour). I think the room needs bigger pictures/paintings or a gallery arrangement; whatever you decide about that, though, they need to be a bit lower. Then play with where your bits and pieces go (the photos on top of the display cabinet make it look messy and less stylish; can you put them on tables or, perhaps, hang them on the walls?