I was thinking of 2 ideas for the position of your toilet... the green option is great as it’s out of the way, under the stairs but reduces the middle room and the toilet pipes are far... Or the blue option: reduces your kitchen, but great for the pipe just above. It depends on many things... Do you have children, in that case, they might need space to play/toys... Do you want 2 dinning areas? Ie: breakfast and middle room... I would personally change the window in the middle room, for a French door... and take the wall off as you mentioned. This would create a nice spacious dining room. I would use the breakfast room as a comfy snug to watch my garden grow while reading a book with a coffee!

Thank you all for replying I really appreciate all of your help as it is starting to take over my life thinking of solutions!! Love some of the ideas. We have about 10k to spend on sorting it. We have to access from the back as its too far to get in from the front door. We did consider turning utility into an entrance with storage and moving utility room upstairs into a bathroom which isnt used. It’s a 3 storey house top floor has a shower room, middle floor has 2 bedrooms both with ensuites and 5th bedroom which is an office and main bathroom which had never been used. Only concern with putting utility upstairs is whether it would put people off if we came to resell? I have been using ikea kitchen planner but I am getting lost in whats the best solution. One is taking removing part of kitchen/hallway wall but means W/C is in the kitchen which unsure off too. Another is making island smaller, removing seating and adding peninsular, other is making kitchen smaller and putting utility at the front of the house but will lose the lovely big window in the kitchen. I will attach some photos

We did option 1 (and love it), neighbours did option 2 (and am sure they love it), so both options work. Regarding light levels - think about how dark your kitchen is at the moment - it'd probably be lighter post-extension as you would knock through a bigger doorway into the open space and there will probably be patio doors in the new space letting more light in. One of the reasons we did option 1 was because we have room to the side of the house too, so created utility, study and garage there, with WC under the stairs. Neighbours didn't have that option. I still prefer having three rooms rather than just two though - and it was easier to extend without having to take so many walls down.

I recommend changing the door in LDK into folding /sliding door I would recommend to make open plan if theres budget to open the dining room wall with the kitchen (the wall might be load bearing so it might be expensive to remove it and use RSJ) I would open the wall on study to the kitchen and study to the outbuilding This Will create more usable open spacious area or you can close this off to create pantry or keep a study room (now not in the middle and doesnt have so many door) I Will close off the front entrance door in outbuilding to make the bathroom there with frosted glass and better air flow I Will build a wall and door adjacent the previous study and kitchen wall in outbuilding to create division for utility room I Will also move the hallway door that lead to living room near the end wall of hallway this creating more space for bigger sofa