What about keeping the wall between the living room and dining area, but widen the opening between the two rooms and eliminate the doors. As a cased opening, it would still provide definition to each room, but not chop up the space.

You might want to also consider eliminating the doors from the openings off the entrance hall to the Living Room, Sitting Room, and Dining/Kitchen, as it's likely they would be open most of the time anyway.

I concur with the above comment: Just have archways installed rather than doors - not only will it be more open but it will be less costly...
...tho to open the living room even more, consider relocating the LR fireplace to the opposite wall and centering a larger archway to the hall opposite it - where the fireplace is located now.

I might also consider installing an archway or doorway to the left of the fireplace in the sitting room - It will make your sitting room less of a dead end and passage to your study, kitchen and powder room more direct.

Thanks for the feedback. I'm going to get an interior designer to have a look at these and more ideas before I do start. I'd be a bit afraid of leaving things too open as it may make it difficult to heat. Must go look for pics with arches linking rooms now to better visualise your ideas. I had actually intended moving the fireplace in the living room to the other wall. Felt it'd be easier to lay out the rooms tv & furniture that way because of doors & windows...

Open floor plans don't make a house difficult to heat - insufficient insulation and poor weather proofing of exterior walls and windows is what makes a house difficult to heat.

Ya I know that but I suppose I'd be afraid the house would lose some coziness. House design is almost to passive standard so not worried about heating too much. I am concerned about getting the layout right first time though. I can see how openings like would open up my plans. Looking for more like this now. This site is incredible for ideas but I find my limitations by house design limit my own creativeness. Thanks for the help