Here's the link to her page https://www.houzz.co.uk/pro/oneplan/oneplan

Laura There lots of functions/ amenities on the plan which is great. Before making a proposal we would think about each part individually and ask how it needs to work for you, the way you want to live and how the spaces can benefit your experience. We note that you have already highlighted your desire to see outside from the island. Other questions might be- Do you watch TV? If so, do you see the Sun Room as a TV area or the Open Plan area? Would the seating area in the Open Plan benefit from full height views of the Garden? Would you eat at the Island? If so, would you like to see outside when eating? There is often a lot of questions but, this helps assess and balance the needs for all areas which would then help inform the ideal layout.

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?

You can make another door on the utility room to the kitchen direction, your counter space might be decreasing by changing the L shape kithen counter into long counter that only run on the right wall, or reverse the L shape counter to the back of the house by closing of the door in that lead to the back garden, as now your using sliding door this exit can be unnecessary, this way you Will have view from garden while washing the dishes, placed the sink below the window, So if you have guest you can take the grocery straight to kitchen by pass the utility In Utility room instead of L shape counter you can build it on left and right side, the right side counter will sit perfectly on extension side, you can add sink, washer draining pipes as it close to the current WC so it Will not too expensive than placing the utility room in another place