I would suggest that if you don't want to make mistakes in your house then you engage a design professional to get it right, especially if you don't know what you are doing. There is an art and science to good kitchen design, and there are plenty of bad kitchens out there which have been "designed" by amateurs. Kitchens are expensive to build, and most cabinetmakers will build with the plans they are given - they usually don't want to try and correct client's mistakes. Just because you can draw it, doesn't mean it will work. I know how to use a keyboard, but I don't know how to write a best-selling novel. Best of luck, Dr Retro of Dr Retro House Calls

understanding all your restrictions would help suggest other options but the original staircase uses too much space and if you add scaled sized furniture to the original plans you'll see that the meals area is mostly taken up with walkways to the stairs and back door and there's very little space left for a dining table..the stairs have to fit both the floors of the house and it's not possible to reduce staircase space upstairs without also changing downstairs

You won't knock out walls for that budget. That is kitchen refit only. Don't brick up the sliding door, it will make the space impossibly dark and depressing. Better to just lock it and pretend it's a window. The real problem in that kitchen is that corner wall that eats into the available bench space. Is that hiding a water heater or something as it doesn't appear to make sense from the photo's you have. If Ii'm reading that correctly you could possibly move that wall outwards to free up extra bench space in that corner and enable a corner top cabinet. Toaster, kettle will fit there nicely. If that's within your budget I'd do it because it will fix most of the problems with your kitchen. When you have a small kitchen like this an easy way to increase bench space without structual changes is a nice kitchen trolley that increases bench space when you need it and can be parked over near the dining area when you don't. I'd replace the current stove with one that has an induction or ceramic cooktop. Because it's flush you can use the stove top as extra bench space when you're not cooking. Makes the space more flexible. Preferably put in a cooktop on the bench and separate built in oven rather than a freestanding unit. The integration will make your kitchen appear more spacious. With the small space you really do need top cabinets but solid doors are a bit claustrophobic so I'd go with a glass fronted upper cabinets so it doesn't swallow your space but still gives you storage. Also install under cabinet lighting this will help out with visibility when cooking at night. And if possible recess the kickboards to reduce their visibility or change them to brushed aluminium this will make the footprint appear more spacious.

I mentioned earlier to think about dropping the wall next to the stairs to hip or slightly higher height to allow for the TV, as this would further open up the top floor and perhaps show the street art, ie the framed print. I know that you don't want anything else hanging from the ceiling but because of the ceiling height you will need a reverse hanging fan to bring all the warm air down into the room that will sit up there if you don't. The heater is because you had one shown in your posted floor plan, this is one of the fires available on my 1997 CAD program, that's the colour it comes in but can be changed within the program cheers