Personally no Georgian bars on the doors, but its personal preference. If its just the doors and no windows in the dining area it should look fine, and will have a complete clear view out?

You need to consider the space into which your doors open to. Ideally opening out of the new extension. If its not too spacious, or might cause things to be crammed, only then can you go for bifold. Bifold will really only come in handy if you have a problem with space. Do you have pictures or a plan you can share?

I agree with 4 Panel sliding door cause it make it unified with the other windows on the left (each panel in similar width), For the front adding small porch with landing and gable roof Will make it more welcoming I just concerned about the half cladding at the front it gives of the vibes unfinished building, usually half cladding wrapped around all the second story exterior But from the front and back picture you share it seems the cladding of second story on front and back were different color so at least you should paint it the same color if adding cladding to the second story too expensive for temporary I would recommend move the tv so it didnt covering the window, if you add sliding wall in the wall section of the bottom right corner room and use Murphy/sofabed it can be used as guest room Change the orientation of the closet near enterance to get bigger foyer and space for small window to get more natural light Change the WC door opening location so ITS more private and open up the wall so the hall feel more spacious

Agree with Betty Boo about concentrating on greening up the outside view once you have sorted the decking etc. I would put a climber where the cream outside wall is, say a Climbing Hydrangea which self clings so won’t need tying in or any trellis. It’s quite a slow grower and easily cut back if needed. If you can leave a small soil border there to plant it in the ground it would be ideal, although you could choose a big pot. Pots are more maintenance as you will need to water and feed the plant. I can see you like plants so you’re halfway there! As it will be used a lot I wouldn’t clutter the area at all, just paint the plaster to connect with the rest of the room and finish off the flooring. I personally wouldn’t introduce any more colour on the walls.