Mike

Sounds like you need to take professional advice. If you're developing for sale you'll be liable for either income tax & NI contributions, or corporation tax, depending on the way you do it, quite apart from the VAT issue...

In some parts of the UK it's necessary to have a sump too, which could be behind the decision.

On the ground floor the main drawback is the use of the kitchen as a corridor through to the living room and to the back door, which limits the usefulness of the lower half. Difficult to do much about the living room, but access to the back door could be closed off as you already have a route via the utility room. You could look at rearranging that space, as ProDave suggests. Upstairs I'd check the sound proofing, particularly between Bed 2 and the bathroom, and between Beds 3 & 4. You don't seem to have provision for a MVHR unit?

In the course of investigating my own requirement for cooling - - I did come across the Unico Boiler that can do something similar on a small scale, if the heat pump version is chosen. It's a through-the-wall 2.5 kW unit (requiring a pair of 160 or 200mm holes), not very pretty, that can either chill or heat the air, as well as heating a 50L hot water tank (which takes priority over the air treating). I get the impression that it's more targeted at the southern European market and haven't followed it up any further yet, though I may. However at 2,700€ it's not cheap, but maybe there are better deals around. The manual is available to download from here.

Have you come across Postsaver bituminous post sleeves? Would be less hassle than building a concrete wall if they work as claimed. I used them on a new fence last year so will report back in a decade or two...

Since it's on topic, despite the big gap, thought I'd feed back that there are at least 2 companies in the MVHR business selling filter boxes that take carbon filters; Zehnder's NOx filter, and Blauberg's CleanBox (which also provides NOx filtering).

Since the board apparently has a BBA Agrément Certificate, that should have the details. I'm currently looking for a similar product so just tried looking it up and can't find one, and the link from their own web site is dead (at the foot of this page) which is curious...

Personally I prefer my light switches to be on the same centre line at the door handles. Been specifying them that way since well before there was a maximum height.

A separate aluminium ladder, plus DIY hatch. See my post in this thread: You need to choose a ladder that doesn't oversail the hatch when retracted, so it doesn't foul the hatch - or mount it higher than the loft floor level to provide clearance, or choose one normally intended for a hatch on a vertical wall, which will fold entirely out of the way.

Made my last one myself - flap-down painted plywood on hinges in a lining + architrave (though could have been a sleeker purchased unit). Above that a separate 9mm ply push-up hatch backed with 150mm polystyrene, sitting on top of the lining with weather strip between, plus a Brighton Sash Fastener on each side to lightly clamp it down for maximum airtightness.

I've done similar using sheets of kitchen roll from time-to-time.

In 'traditional' construction the biggest risk to the cavity would probably be during construction and from inside, rather than outside - that is, from whacking down the hardcore beneath a ground-bearing floor slab, where the whacker would be working very close to the internal skin.

Bagged or brushed would work. Guess you've already considered the brick bonding - you don't want stretcher bond if you want it to look old...

I'd suggest looking up the Council Tax band of neighbouring properties to give a good idea - you can do that by postcode at https://www.gov.uk/council-tax-bands

I'm currently using an Android phone tethered by USB to an Asus RT-N66U router, and am getting 14Mbps download and 10.6Mbps upload (adequate download and much better upload than my previous landline), with 30ms ping & 11ms jitter. That's on an LTE connection with reasonable signal strength (-94dBm).

See if you can buy a stop end for the duct. You can then use a ProClima or similar grommet to seal a hole though it. I've seen water companies specify that you shouldn't use expanding foam or oil-based sealants as they can damage their pipes, so would suggest not doing so unless you use a product intended for the purpose.

I have to agree with the comments above, to which I would add that having all 3 baths blocking access to the bathroom windows is not great. And the two guest bedrooms are not very generously sized. I think you could make better use of the space and still achieve your objectives.

I'd agree with the planning officer that you should go 2-storey to fit in with the streetscape. An alternative to obscured glazing on the back would be to keep the windows above eye-level. That avoids the argument that opening the window will still cause overlooking, plus the possibility that the obscured glass could be easily replaced later. You can potentially compensate for that with a window on the site wall. I'd also go directly for a full planning application, rather than outline, to narrow the scope for objections. I'm not convinced that you need a planning consultant as the likely problems and possible solutions are fairly apparent. If your council has a design guide / applicable policy then that may give you a good steer, as would finding and documenting local precedents.

You could use a photographer's ephemeris (software / app) to give you the sun direction and height at any time of day throughout the year for your plot position. Using that you could work out what would be in shadow when. An alternative would be to use Google SketchUP to model the site - it can model the shadows too. If you're required to put anything together for planning permission on the topic - unlikely if you're on a rural site - then the BRE guide 'Site Layout Planning for Daylight and Sunlight – A Guide to Good Practice' is the standard reference.

There are also several missing stages between 'initial interest' and 'part way through build'

Not sure if the regs have anything to say about it, but my place has the consumer unit mounted on its side. Though when I rewire the new one will be mounted conventionally.

That will also depend on local custom and practice and what the planners will accept. I've lived in places where it would be no problem having a free-standing garage backing onto the road (facing the house), and others where that would be instantly rejected.

I agree with Ferdinand. Also not clear whether the dressing room is supposed to be that - with dressing table etc - or just a walk-through wardrobe. If the former then I don't think you have enough storage and would switch to storage-only. I'd probably also shift the airing cupboard left, pinch some space from the landing, and then have a separate walk-in wardrobe running left-right, and the bathroom running left-right along the outside wall.

Hope it goes smoothly! Bit late now, but if you have the right software you could probably have used OpenStreetMap for the block and location plans; there's no obligation to use any particular map supplier, as long as you meet the criteria

Looks OK, as long as the clamps are tightly fixed - they will get well tested by door usage / slamming. The brackets will presumably though prevent the plasterboard from sitting flush with the studs, so you'd need to do something to overcome that. No chance of reusing the existing holes in the lintel, maybe using chemical anchor bolts?