Hi Susanne, in order to properly advise it would be helpful to understand what you are trying to achieve and what your budget is.
I’d want to know if you are open to changing the layout completely and knocking down walls and whether or not there is an option to extend?
What is at the end of the kitchen outside? Is it a terraced house? Is the other side of the house going to stay as is? Who lives here etc.

So it’s an end of terrace for a family with dogs. At the end of the kitchen is the garden which I wouldn’t extend into as it’s reasonably small. There is side access to the right of the property.

At the moment the back door next to the shower doesn’t work but I would like to keep either a door or dog flap somewhere to access the garden.

Budget of £20k for building works as required for windows/doors/walls etc

Hope that helps

The roof over the rear part of the kitchen and shower room is a flat roof

I assume the 20k budget is for the building works, and then you have extra budget for a new kitchen, shower room, toilet etc.
To avoid too much structural work and save your money for a new kitchen, shower etc, I would take out the kitchen window and open up the entire wall here to install full height windows that span the entire width of the house and look into the garden.
If you opt for bifold doors, you could even bring the outside in during the summer months. It would open the whol soace up and bring in much needed light.
Then I would use the entire left wall of the kitchen for your cabinets etc. It lends itself to this perfectly as you can’t have any windows there, if I understand your correctly.
To keep costs down keep rooms as they are but redesign the layout of the utility shower room, toilet etc.
If you’re interested in additional help, my prices are very competitive and I could draw you up some floors (in 3D if you like) to give you some more ideas.
We could look into clever design features to see if we could bring in even more light, whether the other rooms could be rejigged and also start planning your kitchen so it has a layout that is practical but also looks great.
I offer a fee 15 minute introductory chat too, if you want to find out more about I could help and how I work.
Best wishes,
Tessy

Oh and if the roof over the rear part of the kitchen is flat, I would explore skylights here too of course.

If feasible i would:

-make the current utility a combined boot room/utility, with a separate shower room. swapping the utility to the opposite side where the small window is and creating an entrance door from the side access.

-i would open up the rear kitchen and shower room and put a roof lantern in the flat roof and insert a side window for added light and have this as the dining area /kitchen.

-as previously mentioned the left party wall (and the utility wall) for the kitchen.

- patio doors to the garden

Do you see yourself using the sitting room to the right of stairs as a sitting room - due to position it looks like it may be used as a corridor so would actually make a decent dining room unless you have earmarked for anything else. It looks like your utility and shower room need to be swapped so you have access from utility to the outside not from shower room as I would be worried about people going in or out the side door catching me in the shower! Probably cheapest to keep toilet in same position due to drainage. If happy with my suggestion to use sitting room as dining then your kitchen can extend into the dining area - as it is narrow a galley arrangement would work best I think and you could replace window at end into door to add light in. Lots of potential I think

Here’s my very rough sketch! Dining area in sitting room. Door to shower area for privacy. Move utility wall to create small pantry and utility area now accessible to outside.

Alternatively move your back door, use the middle room for a shower room and dogs room and then make this space at the back into the best room in the house.

We were hoping to use the middle sitting room as a cinema type room for the kids etc and keep the front sitting room as an adults area/quieter room.

I definitely want to keep a downstairs shower and utility room.

Happy with suggestions for alternatives for the middle sitting room as it is a bit of a walk through. I’d be happier to use the back of the house as the main entrance for boot room and then that’s the area we would use most for entertaining etc.

This house is on the Isle of Wight and I’ve been told it’s tricky to find decent trades on the island if anyone has any recommendations

I think Kat Lucy’s design works well then for what you want as you gain some space for dining overlooking the garden and have simple utility/bathroom as well