My first thoughts on looking through the photos without reading anyone else's comments:
Picture 1 - doesn't make your house look detached -- it looks either attached to or crammed up very close to its neighbour, and it doesn't look very big. Would it be possible to retake a picture more head-on and without so much surrounding detail?
Picture 2 - looks a bit dark. I'd be inclined just to brighten it up a bit in Photoshop (see below)
Picture 3 - dark again. I'd actually ditch this photo and stick with Picture 4, which makes your kitchen look much bigger.
Picture 4 - but I'd still brighten this one up a bit.
Picture 5 - does your estate agent know how to use a camera? This is dark (quite an achievement for a conservatory!) and the colour balance is off (I bet they were shooting on tungsten white balance inside and didn't bother to change it to allow for the natural light see below). This room could be staged to look more inviting for photos, I'd move the table more centrally, replace the vinyl tablecloth with a table runner, and set for a meal with a bowl of fruit or something in the middle of the table.
Picture 6 - same problems as picture 5, plus I don't think it adds anything.
Picture 7-10 - fine.
Picture 11 I'm struggling to relate this to the floorplan is it a very small room? A space on the landing? I'm guessing the latter, but if it's not presented to make that clear someone could think your fourth bedroom is minuscule. Can you make its context clearer by shooting from a different angle, or consider dropping the photo and leaving it as a nice surprise for viewers?
Picture 12 - fine
Picture 13 - there's nothing wrong with it (although if you want to include this view I'd be tempted to retake with a nice blue sky rather than it being whited out) but I don't think it really shows off anything about the house or garden. If you've got a nice sitting-outside area there it might be better photographed from the garden side.
Picture 14-15 -- these are fine, although seemingly odd framing choices. I'd be inclined to tidy up the paved area around the shed and maybe put in some more colourful flowering plants in pots, but the pictures do show off that it's a good-sized garden ideal for children, which is your major selling point.