I can imagine you must be demoralised because you can’t afford what you were dreaming of but I have got to say I get excited about this kind of house, it’s amazing high ceilings and finding one at an end so the garden is not shaded is brilliant. I think you could have a beautiful space if you put bifold doors between the kitchen and the lean to, raise the floor in the lean to so it’s the same height as the kitchen and have the same flooring for a feeling of continuity. The bifolds satisfy building regs as you don’t need to rebuild the lean to, you have a dining space for all but the coldest days and when it is cold you just close the bifold doors.

If you are going to take out the wall then it won’t matter if you make a mess now. So take a hammer to the wall, knock a hole and check if you have bricks/block work behind the plaster. If it is indeed non structural it’s most likely it is a wood frame with plasterboard. If this is the case then a builder can confidently take it out. If it is solid behind the plaster then you will need building regs and a structural engineer. You will probably need freeholder permission too.

I think if you research resale values you will find adding an extra bedroom will add value but how much will depend on the compromises made. Personally I think that the chimney dividing the second bedroom is too big a compromise and would be asking for estate agents if you will recoup your renovation budget if the bedroom is divided. If it were me I would build a case to present to the freeholder: Get your structural engineer to write a letter that explains that a building that has had underpinning now has stronger foundations than the original and should not be a concern. The letter should also mention that steel is stronger than the original brick and your work is covered by insurance. You should also get something in writing from your preferred builder that explains the timescales - knocking out a wall and putting in a steel can be done much more quickly than people think. It sounds like you could also help your case by agreeing to inform the buildings insurers, paying any required extra premiums, offer an incentive that you could organise (although not necessarily pay for) additional building repairs while the builders are in. Separately I would not consider living through the work- this property is not big enough to find somewhere to escape to. You should move your furniture out and give your builders the freedom to get it done quickly- this will likely make it cheaper and offset the costs of moving out

Hi! I studied architecture in Edinburgh! If this is not your longterm home and ensuring return on investment is important to you then I recommend getting some sketch designs and talking them through with local estate agents who are familiar with the local housing market. You could show them a couple of options and get their opinion on which is likely to get the higher resale value, or which is likely to sell quickest - sometimes you don't get a lot more money but it's a configuration that is more sought after so it sells faster, which can also be a benefit when you come to sell. Most of the work I do is creating more open plan living, this is the general trend and has been for the last 20 years or so. I redesigned my Edinburgh flat to have an open plan kitchen dining lounge and it sold for the highest price achieved in that tenement or that street, though I did get lucky selling at the height of a market bubble at the time. I have a free Design Your Home Vision Checklist that is a good place to start with a home redesign: https://www.i-architect.co.uk/dyhvchecklist.html Good luck with your project! Jane :)