Ok, I'm going to go through pics one at a time
Pic 1: Storage units at each side of the fireplace need tidying. No wirs should be seen. Clear mantelpiece completely. the fireplace is lovely and needs to be allowed to stand out. I don't know what's behind the door into the kitchen, family noticeboard?? but it needs to go. Speakers look a bit odd hanging from the wall, could they go or be moved? Simple fresh flowers in vase on table.
Pic 2: Lovely garden, perhaps remove washing thingy.
Pic 3: Remove pics/items from behind bed. If they leave holes perhaps buy one large ikea type print to cover them. Curtains need replacing as does duvet cover to match rest of decor. Perhaps paint walls a more neutral colour, have white bed linien and a bold psttern for curtains plus matching cushions on bed. I had my bedroom walls a similar colour in my old flat. It wasn't till I moved out that I realised how strong it was, I'd just got accustomed to it and hadn't really noticed it when I lived there. Remove rug.
Pic 4: Completely declutter mantelpiece. Decide if this room should be dressed as a receptioin room or a bedroom. Ask your agent's opinion, they should know which will be better for the value of your home.
Pic 5: Tidy up! Drawers should all be closed and hiding stuff. window length curtains, remove paintings from walls. Ask for better angle of photo. This one gives me no real sense of the proportions of the room.
Pic 6: Remove rug.
Pic 7: bin should not be in pic. Clean surface of vanity unit. Hide any toiletries that cost less than £20/bottle.
Pic 8: Hide wheely bin. Move cars esp white one.
Pic 9: ditto pic 8 comments
Pic 10: Again move noiticeboard. Get rid of item to the left with different shaped holes in it. Bin should not be in shot in kitchen nor should those little pots on the floor.
Pic 11: Remove magnets from side of fridge frezer. Remove rack thing from bench and handlotiion from window sill. Oil worktops. Is it possible to open back door into garden completely so that you can see into garden without seeing dorr itself? That would look better.
Pic 12: Again remove noticeboard thing. I would be tempted to declutter the pots and pans hanging in the ktichen but not remove them entirely, give people the idea of how it could be but don't let them think you've got no storage for these items.
Pic 13: Nice pic. Remove child's stripey chair.
Pic 14: Nice pic.
Pic 15: Nice pic. Is there any way that you could add some more colour to the garden?
Can't believe how long this post is but I hope it's helpful. I'm trying to be helpful and dispassionate as I don't really "know" you iyswim. Good luck!