Your photos are terrible.
Sitting room:
You need to take all the family photos and the collection or whatever is lower down off the shelves in the sitting room, and arrange a few books neatly, some stacked, some standing up in their place. Maybe an artistic looking object or two as well. Your lamp needs to be out in the room a bit. Lose the blue box and maybe also the two stacked boxes (old suitcases?) near the lamp. Lose the green rug too. Get a light grey or cream fluffy one instead. Straighten the couch cover and the cushions. You need a photo of the view from the window. Take away the flower picture and hang the tigers at the same level they are at now but over the couch. Leave the window wall bare. There is enough there with the window. Put the plant to one side on the windowsill, not bang in the middle. Putting stuff in the middle divides the space in half, visually.
If there is a presentable chair under the purple cover in your bedroom bring it down to the sitting room and create a little interesting and alive space between the fireplace and window wall with the lamp moved out from the wall to at least halfway across the shelves and not directly up against them.
Your fireplace looks bare, and also fake with the wainscoting running at the bottom. Maybe take off that wainscoting (or paint it the same colour as the dark tiles) and tile the floor in front with black rustic/ limestone tiles extending about six inches into the room to suggest a plinth, and then put a selection of tall and medium potted plants of different textures on the tile - five should do, arranged 3/2 with the space of one plant in between the 3 and 2. Don't space them equally or line them up straight. Get rid of the hearts by the fireplace, and also all the photos and everything else on the mantel. Replace with a few black candlesticks of different shapes and white candles.
Can you take down the current fireplace cover at all and recess it considerably instead? Is it a real fireplace? Your house is old enough to have had one.
The wallpaper and painted wall colours in the sitting room are screaming at each other. I would repaint in a colour that is closer to the colour of the vines/stalks in the wallpaper. Choose a light tone, not deep (a mauvey grey?). The colour should complement your couch, but don't go as deep or dark as the couch. Maybe www.dulux.co.uk/en/colour-details#cool%20neutral Misty Mountain, here? I would paint over any wallpaper that is not on the chimney breast, leaving the chimney wall the only feature wall. You will lend greater depth to the alcoved areas that way. Paint the pipes in the far corner the same colour as the wall. There is no need to pick out details like this. Get a new dark grey or black lampshade, or cream to match the ceiling one. Get more of a drum (horizontal) shape.
You need to swap the chevron cushion near the window for the one in the corner facing the shelves. That part of the couch is a chaise longue, and the extra element of relaxation associated with that feature should be emphasised. Take the small white cushions away from that part too. Put them elsewhere on the couch. Maybe get a nice cream and grey throw to drape at the chaise end? I would also put a nice big potted plant between the end of the chaise part of the couch and the shelves, on the left side of the window but not lined up with the window upright. If you put your cursor half way between the end of the chaise and the suitcases (?) in the photo, that is the spot to put the plant. You need something with a decisive shape, not wispy and not vertical, that comes to just under half the height of the lower window pane including pot and saucer.
Main bedroom:
Take the shelves off the wall. Leave that wall with only the window and curtains. Change the purple duvet cover for a white one. Tuck it in at the foot of the bed so you show the bedframe. You want to avoid the sense that stuff is all over everything. Get rid of the purple thing from the corner. Maybe bring up the two suitcases from the sitting room. Get rid of the boxes under the bed. Put nice candles on the bedside tables. Put a nice indoor plant on one bedside table goo.gl/images/1i9WJN . Photo needs to be taken further back.
Plants and candles suggest restfulness, relaxation.
Second bedroom:
Take all the posters off the second bedroom wall. Tuck in the duvet a bit. Lose the stuffed animals and clutter on top of the wardrobe. Take away the little figurines from the window sill. Replace the blue blind with a white one. Get rid of the little blue bedside table and bunting. Stand further back to take the photo.
Kitchen:
You need another view of the kitchen too, even if you have to climb up outside the window and stick the camera inside. Clutter on top of cabinets, and on the counter near the window must go. This includes your kitchen utensils and their shelfy/hangy thing, and the oven mitts. You need to group your plants better on the window sill. Plants will draw the eye and suggest that this is a kitchen that is not so small that every spare inch counts, unless you have them arranged the way you have them now. You need to put one plant on the counter in the corner (biggest plant) where the utensil thing is now. The rest can go on the left side of the window sill, in ascending order of height, on the left. Get one more plant to achieve a 1/3 relationship among the plants (one on the counter, three on the sill). When you take new photos, take the basins out of the sink.
I would be very tempted to repaint the kitchen in Dulux Tuscan Terracotta or maybe Copper Blush www.dulux.co.uk/en/colour-details#orange. The beige of the tiles is not in the same family as your yellow paint colour. The white cabinets would look nicer too with different walls. White often takes on a grey or dirty tone when paired with yellow.
Bathroom:
Stand further back to take the new photo. Clean up the area with the pipe (?) between the loo and the bath, on the floor. It looks grubby and suggests a water problem down there. Cover up with white paint if necessary. Repaint the walls a nice clean blue - www.dulux.co.uk/en/colour-details#teal Blue Reflection might be nice. Paint all the woodwork white. The wood rims to the tiles and the wood surround of the bath look cheap and make the space look smaller because they divide it up, visually. Use a basecoat, then white gloss. The shampoo and soap holder things above the loo need to go. They only emphasise that there is nowhere else to put them. Take the ornaments off the window, find a tall box or rectangular potted plant pot in white or light terracotta, and put the shampoos in there, on the window sill. Or put up a long, tub length shelf above the tiles that can extend as far as the sink tiles, and put stuff on that.. Take the toothpaste holder thing off the wall too. You can keep toothpaste, etc in a little basket on the floor under the sink if you don't put up a shelf, and on the shelf if you put one up.
Tbh, if I were buying your house I would want to rip out the bathroom and put in a bath/shower, retile and put in a basin with unit underneath. In the end it wouldn't matter that it is now brown. But the brown paint and other details look really bad, and you want to avoid putting people off, because unless you sell to a rehabber, a family is going to have to live with the bathroom. People need a bathroom so you should make it look as if it is a usable space that doesn't require immediate work.
I would also want to extend the kitchen and second bedroom out into the garden sideways, and knock the dining room and lounge together, sectioning off the stairs (are they in the dining room now?) and creating a new front door area, maybe relocating the manhole.
You need dining room photos and the flying freehold needs to be mentioned in the blurb.
Your floorplan needs dimensions. It's not easy to refer to a separate page (Description) for these.
Garden:
Front is nice and neat. Add potted box shrubs and big potted plants - three should do - near the downspout in ascending order of height from left to right to soften the border between house and gravel, lead the eye to the gate, and make the front more homey/welcoming/cared-for looking. Add another four or five in front of the section of fence in the front, with one level as the front of the house, though at the right side of the path. This will emphasise the entryway/gate and draw the eye forward.
Get another few bags of gravel and spread it evenly in front - it looks sparse, and there is one bare patch in the photo.
In the back, get a strimmer and neaten up the grass edges. Mow the lawn. Put down mulch by the fence. Put the paddling pool away in the shed. Put the big blue slide away too for the purpose of photos. Add some chairs and put up the umbrella.
Put a cheery outdoor mat outside your front door - looks as if you had one there before?
Stairs:
It would be a big job to paint over that wallpaper but I would do it. I would use the same colour as the landing. The reason to paint it is that people might not like it, and would worry about the work involved in painting over it or tearing it down themselves. At least with white walls people are looking at a blank canvas. A blank canvas is energising, whereas wallpaper in a bold colour and assertive pattern needs a good deal of prep work in an awkward space before they can get started on making it feel like their home.
The picture on the landing needs to go. It's way too high anyway.
Issues:
The pylons - marmite issue. Nothing you can do about them. They are what they are. Some people won't mind them. On top of that, there is the flying freehold.
Given the issues, you can only aim high if your decor is nice and potential viewers won't be put off by it. At the moment, your house is a mishmash of unrelated colours and tones and it looks cluttered. You need to do a better job of making the most of what you have to offer, and neutralising negatives.