ProDave

The lintel that squares off the door opening is not really doing anything structural. Nothing will fall down if you take that down. The piers are usual construction at intervals on a single brick wall. I would suggest whichever way you widen the opening which will mean taking down one of the piers, you will need to build a new pier at the other side of the new opening. Then you can span a new lintel between the new piers over the opening. Post the dimensions of that timber supporting the roof, and the proposed width of the new opening, and one of the SE's on here will hopefully advise if it is okay as it is to span that distance or will need strengthening.

Can we see a picture zoomed out a bit for context. There is some dodgy wiring there.

We did a slow "build as you earn" due to inability to sell the old house. Instead we let it, to give income, moved into a static caravan on site while we completed the build. We started to use more and more of the house as it progressed, while still officially living in the 'van. It was self build insurance renewal costs that tipped us to getting a temporary habitation certificate to move in and swapped to normal house insurance while we finished off. Living on site should NOT slow it down, if anything it will speed it up because you are already there, ready to go and work on the build when there is time to do so.

Post the full quote and we might be able to advise. Any pictures of the site etc?

Moving soil with the dozer blade When I was doing my groundwork I wanted to clear all the topsoil and pile it up at the edge of the site. I did not find a cheap enough dumper close enough so was doing it all with my 3t digger. So I used the dozer blade. Piled up a load of soil in front and pushed it. After a few runs, what spilled out from the sides formed a trench and thereafter not much escaped. Once pushed to the edge, used the digger bucket again to pile it up into one big pile. So it can be done. Beware once you get up to about 6 ton not all diggers have a dozer blade.

I would expect a modern 5 year old HW cylinder to be well insulated. I would be looking at the pipework to make sure that is also well insulated. Pictures? Our airing cupboard is perhaps 2 or 3 degrees above the room it is partitioned from, not much at all.

For moving soil I would be looking for a JCB 3CX etc not tracked digger. You can pick up a front bucket of soil drive to where you want it and tip it. A 360 excavator is pretty poor at moving soil, that would be a bucket load at a time, or using the dozer blade to push it around. Unless you want to buy a dumper as well?

You are not buying the right house for you. You are planning to buy a house that needs alteration and know access for tha alteration is going to be difficult. Can you not find a semi detached house with side access or at least a terrace house with access to the back garden other than through the house. Direct access to the rear garden was always one of my non negotiable requirements, for simple practicalities like I don't want to have to transport the lawnmower through the house and back again every week in the summer.

No help in an existing building, but this is just one of the many reasons I think all new roofs should be built at a 45 degree angle.

I suspect those walls are supporting the roof purlins at either side. So treat them as structural. The only way to get enough headroom for taller doors, is move them towards the centre a bit. The headroom at the edge is what made them put small doors there.

In your dreams. It would put some people off. A friend of swmbo was house hunting, they had the chance of a semi detached house with solar PV at the original FIT rate, and also had a paddock behind it. They withdrew from the purchase after the surveyor warned the PV panels may affect the integrity of the roof, and the paddock was outwith the village boundary and in green belt so they could "never do anything with it"

I would have lost patience by now and told them I will be serving eviction notices and marketing the property.

Perhaps you could post the quotes you have got? Just because there is for example a cable right outside your plot does not mean it has sufficient spare capacity to connect another house for instance.

The pipes are probably okay, lazy plumber did not wipe flux off after soldering and it is corrosive.

Aren't FD door liners supposed to have recessed grooves for over size door stops? (mine did) I always fit door stops at door hanging time, one less thing to line the doors up to. Instead line the door stops to the door.