You’d be surprised how many people don’t have any imagination and concentrate on irrelevant things when viewing, or deciding what to view.
^This is very true IMO. I took MIL to look at houses and she couldn't see past even minor things - in one there was a lovely open plan space which was effectively dining room leading to kitchen, but they didn't have a dining table and instead had it set up as a sitting area. She couldn't see past this. To her mind there was no dining space no matter how often it was highlighted. She rejected places because she didn't like the wardrobes, the decor...
I've just sold my own place. Decor is not neutral (my front door is magenta!) but it was very well staged, every room laid out well and properly presented and it sold in days. It's not necessarily about loving every element, but about people walking in (or looking at photos) and getting a good warm feel that is somewhere they could make home and being able to see how the space can work. I think this is where folk struggle more - less about colour and more "where would I put an x, how would we fit everything in, where do we eat, where can I work"
Personally I'd consider the following:
Get the EA to put the dimensions ON the floor plan. Flicking between description and floor plan is annoying! And a wide angle lense would help - I can take better photos on my phone!
You want to play down the length of your sitting room (mine is similar size). I'd lift the second rug I think as it seems to emphasise "this room is loooong, look it even needs two rugs"
There's no eating area in your kitchen and the photos look like it couldn't fit a table even though it almost certainly can. Many people wouldn't want to carry plates of food from the kitchen, through the living room, to the extension. I'd get a small table in at least. I'd agree with the suggestion to consider painting the kitchen units a lighter colour.
Get the main front door on the floor plan, and get the coats out of the kitchen. Viewers should enter in to the hallway and the kitchen should be a defined living space not an entrance corridor
Tidy up the extension and get a better photo - I think it's much bigger than it looks? If you are using it as a dual purpose playroom/dining room that's ok, but in that case I'd rotate the dining table and then create a defined play space at the other end (Outside the kitchen window) with neat toys, kiddy sized table and chairs, something like that. The space looks unloved just now
Master bedroom - I'd suggest a photo taken from the door towards the bed and window. Your TV is not a feature! Get some curtains up in the same colour as the bedding, make the bed properly, add some extra cushions. Get rid of all the clutter in the corners. Couple of lamps on the bedsides, take down the (oddly small and high up) picture above the bed and maybe put a nice print above the bed instead, or get a headboard!
Boys bedroom - make the bed, lose the gaming chair, sort the curtains, take all the little stickers down. The bigger decals are ok IMO, but the wee round stickers screams "my kids get let loose at the walls and they've probably crayoned everywhere too"
Pink pedroom - lose the chair and fan, and the box of stuff under the desk. With the chair out you could probably pop in some sort of neat storage for the contents to go in, a small chest of drawers or something.
Gardens - cut the bushes and get a few nice planters with some colourful flowers out the back. It doesn't need to be much but it will make it look much more inviting. Sort the bottom of the shed. Move the slide to the back of the garden beside the shed so it's not so dominant in the photo. I'd actually probably delete some of the garden photos too, I think the angles of 23 and 24, and maybe one looking back at the house, is enough.