You need to put all the dimensions on for a real feel for the place. You would also need to instruct and architect and a structural engineer. A concept planner could really help to give you an idea of what's possible and open your eyes as to what changes could be made. I doubt you need to seat 22 on a daily basis, but you may be able to get two dining tables in on occasion. ( We keep another table and a set of chairs outside in a store room for such times ). We have one table that seats 8 all the time, then the other that we bring in which seats 6 more. It's a squeeze, but we manage. Thus I had a little shuffle about and came up with this as a 'concept idea'. Clearly specialists in their field will be able to help a lot more:-

We have the exact same layout and decided not to extend the living area. There already was a mudroom/utility extension. We did remove the reception-dining wall and chimneys, removed the kitchen-dining wall. Our fridge freezer and oven are in the mudroom. And I cut a rectangle out of the toilet-kitchen wall to make room for a small toilet washbasin, the hole is patched with plywood and tiled on the kitchen side. The desk is next to the dining table, only need to turn the chair around. NB we do have a small cellar where we store food, oven trays and such.

Jonathan, funny you say this as my first sketches were for sink where hob is and a floor to ceiling window looking out to garden! for the exact reason that sink there is 'traditional' so I totally get what your saying. the reason we changed from that plan was at that point the hob was on the island, when we changed that idea I then wasn't sure about both hob and sink along the run of cabinets, both facing a wall, wondered if we would feel we'd made the kitchen boring and antisocial as would always be facing the away from the room? and lack of pantry we were quite pleased with the extra cupboards it brings. the understair we will be taken out so the garage conversion bathroom will be the only we on ground floor, the bath is a must I'm afraid as we are really missing it and don't want to cramp the upstairs bathroom by putting one in as that's the high use shower. I've always assumed air con would be expensive and ugly? we are going for electric velux sky lights so will be easy to open. thanks for your input, always so helpful to get other perspectives.

Its hard to give a full breakdown of options without studying the full plans, your requirements and budgets. This is something you need to do with your chosen Architect. However, there are many options for adding windows and ways of making light bounce around the house, but if your architect has said you can't add more glazing you should ask why. I would suggest it is because it will start to impact the thermal efficiency of your house. North facing windows get no solar gain so by adding too much you could end up with a house that is difficult to keep warm especially if your house is older. You could upgarde to super energy effiecient glazing but of course that will come at a cost. Having looked at your existing plans it looks like your house has already had extensive work done. Unfortunately it doesn't appear like an architect was involved. A lot of the cost of your renovation will be in correcting previous mistakes and even then you will end up with columns in ever room unless you are willing to pay to have that corrected too. The cost could make the option of moving more viable? Did the previous owners also extend upstairs?