bassanclan

If you are anywhere around the west midlands have a look at Eurocladdings, especially if you are not looking for a specific tile and would consider a 600 x600 tile, they have some end of line stuff from under £10psqm

https://buyroofslate.co.uk/slate/spanish-roof-slate/500x250/castillo-spanish-500x250/ If this is 75p, try for 50p

You could have the decking stepped so none is more than 300mm above tge existing soil level, or dig down on on side, by say 700mm and then have a level decking all the way across

I can appreciate the time and skill gone into @Carrerahill 's worktop, but it's not something I would ever do. If there wasn't room for a clad on end panel I would have had to replace the side panel of the tall cabinet/oven housing to avoid a bit of worktop jutting out.

As a self builder you would apply for exemption from CIL anyway before starting the build, so don't let that be a reason to keep to an inherited design etc.

I think the whole upside down house might be a mistake as you are missing out on being able to have french doors/bifold doors out from the kitchen/living area onto what looks like an expansive plot with countryside beyond. It is all very well designing a house for just two of you, but hopefully you will have friends and family visiting and you need to consider that when designing, otherwise you may as well build a 1 bed house. Also at some point the house will be sold, by all means make it your own, but a 3/4 bedroom house has to ultimately be a pracital as a family home.

Not sure I'd want the door to my master bedroom opening onto the main entertaining space. Especially into the dressing room! Are there good views from the Master bedroom? Would an office and snug not benefit from those views, rather than the bedroom?

Can you trim 20mm off the back of the worktop so it sits nearer the wall?

Not sure if you need a hole for a waste, but you can't drill glass once it has been toughened, it just shatters.

Could you not use an offcut of granite/quartz? If you have a local supplier they will have offcuts or look on ebay etc. Or maybe a piece of toughened glass might look good, particularly if frosted.

Tracksaw might do the job?

Yes 12mm hardie backer board can be used for the celing of a fireplace opening. Depending on size you might have a metal plate up there anyway. This might be a useful start of reading https://www.stovefitterswarehouse.co.uk/pages/lining-a-fireplace

I'm not 100% clear where your dining table is, if in the garden room access is a little awkward for people coming from the open plan living area. Would the kitchen ar the far right work better, with more natural light and better outlook?

I presume you are building over an Anglian water sewer and have asked their permission?

Are you having a block and beam floor? If so how many courses above the lintel to the beam and will a beam be resting on the middle of a lintel?

If you are comparing structural liquid concrete (such as agilia) to sand and cement screed it will seem expensive, but if you are putting in a concrete subbase and then screed on top and accounting for labour then the agilia looks more reasonable.

The first question the designer is going to ask you is what budget you have for the work. For example the cheapest indian sandstone will be £17-20 per sq metre, with a subbase and labour on top. Turf might be £3 per sqm etc. You really need to make a list of what you will want from the garden e.g. veg garden, football pitch etc etc

But ideally you wouldn't skim tge parts that are getting tiled

See if you can find a streetview pic of the tall bushes to support your argument

I used 0.3 as I was replying to your quote. A U value of 0.3 was the old requirement for new extensions (which I guess you looked up) it should be 0.28 for both garage and porch and other extensions.

It may be that everything was previously painted in an outdoor varnish etc made to resist water and you are trying to paint on a water based paint. If it is old varnish it needs to be removed/sanded

The reason is that the elements are NOT existing as part of the dwelling. They exist outside the thermal envelope of the dwelling. Porches, garages etc are not built to be part of a dwelling, so if they are added to a dwelling it isn't a refurb it's a new habitable space.

A garage conversion would also need to meet a u value of 0.3. If you actually want to comply with the regs on this porch then the roof and floor need insulating too. The 0.7 u value is only for a refurb of an existing dwelling not adding rooms/extensions to it.

If its his chimney and his aerial it looks like your gutters and fascia and maybe foundations might be on his side. Just a thought, but how are you going to proceed if you say no, don't attach to my wall and he then says, ok get your gutters and fascia off my land and btw, you cannot discharge your roof water onto my land either!? So be 100% sure that your extension is on your land only before you start. Either way at some point you'll want to be in his yard to paint your render. You have no overlooking issue thanks to your extension.

Have you looked on https://www.old-maps.co.uk/#/ To see when approximately it was knocked down? If it doesn't currently exist there can be no permitted development. It's often why you see applications for DEMOLISH and rebuild.