I think you’d need to relocate the wc and basin to form a shower room /ensuite -so need more info on soil pipes at this end of property ... if you could put ensuite in bottom right with bootroom bottom left will leave the top area to be guest room and small snug or dressing area perhaps ? Overall it’s about 5.9m x 5.8m so there’s room for a few options - but possible placement of soil pipe is the bit anyone designing this would need info on.

Hi Sophie I think your room is a lovely size with great windows - they need some curtains to soften that end of the room I would suggest. I particularly like your floor which is a warm colour. My choice would be to pick up the tones in the floor and use a buttermilk colour on the walls - something like Travertine mid from Little Green on the walls, travertine light on the ceiling and Travertine on the woodwork. If you banish the greyish rug and look for something either with deep pink or burnt orange colours in a pattern and pick that up in a pattern on curtains and some of the cushions together with a lime green and an aqua blue to add some freshness. I agree bigger plants and find a stand for a big plant. Lighting - if you can access the ceiling more downlighters would be great. You could change them all to dimmable and ensure they are warm light. I also use up free standing lighters. The one in the photo has three brightness settings and is great. If you repeat you bookcase on the other side of you door you could use LED light strips above those. We have some under and above kitchen wall cupboards which are on all day in winter in our east facing kitchen. They give a lovely warm glow. Carefully chosen paintings/prints to pick up colour from the sofa and rug and cushions. Have fun.

Full width extension, 1.7m deep. Toilet next to front door, utility with stacked washer&dryer, shelving and a bit of worktop, under stairs storage. Opened up some walls to create an open plan living. Kitchen with 4 tall units (one for fridge freezer, one with oven). (to return a favour paypal.me/rinkedit)

And personally I think that in order to get more light to the front bedroom you either need to add a rooflight or accept that they are north facing and decorate them differently.