If I were starting from scratch, keeping the front formal sitting room as is, I'd have the large entrance hall as combined formal dining, put the shower room across the hall and the utility, so taking the place of the planned kitchen and then do a kitchen/eating/lounging room right across the back accessed directly from the dining part of the hall. The kitchen part would be where the dining area is now, so only accessed by those who need to and with direct access also to the utility room.
That may cost more or be a bit impractical depending on where the downstairs toilet could reach to the foul drain?