Hi Fran, I would remove the wall between the kitchen and dining room to make a large kitchen containing a dining table. Keep the drawing room as your living room as it look like it's the bigger between sitting and drawing room. I would keep the sitting room separate because when you are blessed with children you can use as a toy room and shut it off. Trust me there will be days where you will just want to shut the door and not deal with the carnage inside it till the morning! I would however try to add perhaps some sliding doors between this room and the new kitchen/diner so you can keep an eye on the children when they are playing. Later on you can use this room as a games room or study but you have the option of opening it up when you need. I love bi fold doors, it makes such a difference to the feel of your rooms, ours just open up the kitchen to the garden. Make sure one of the panels is a door. Downstairs WC and utility room is a must too, I would keep those as they are. Good luck!

The architect should really have supplied dimensioned drawings however I don't know what your agreement was so... 1:100 is the scale, it should give the paper size too. For instance 1:100 @ A3. Or A2 etc. This means that when the plan is printed on that size paper it will be accurately to scale. The architect may have given you a paper set of drawings rather than a digital email file, in which case these should be to scale. With a good quality rule you can scale off these drawings. One millimetre on the drawing will equal 100 millimetres in real measurement so 10mm or 1 cm will equal 1 metre or 100 cm . This is a really easy scale to convert. Good luck

This product leaves me cold...

I use HouseDesign which is a Free App on my phone. You could also use the more sophisticated RoomPlanner that has a subscription. Alternatively employ a designer or concept planner to envisage several layouts more cost effectively than using your architect. You could also post the entire plan on Houzz for creative input from the community. Personally when I look at the plan I think that the space is made narrower by the two sets of stairs and the original stairs obscure flow from the front to back. Perhaps having one set of stairs in the centre of the house creates problems upstairs but I would be considering it as it might mean you can build less square footage and make a cost saving. Additionally the largest reception room seems to be on the lower level with borrowed light and in my opinion perhaps less frequently used rooms should be there with the living room further up the house.