Conor

No need to fix down once you get worktops on and fill the cupboards.

Is it just a vent pipe or is it a function stack? If it's just for venting, bury over it, fit another one somewhere else, or use a combo of air admittance cables instead.

200mm is a bit out of what you could call a margin of error. we did similar, ended up 250mm too high by the time we got up to the ridge. I made the call to drop the wall plate by 100mm and the ridge by 150mm. So we edend up about 100mm too tall. Could not got away with any more as we set the ridge height to be mid way between the houses either side of us. It depends on your design and construction method, but trimming 100mm off your ridge and wall plate might help you sleep at night. we were building ICF and a panel roof system, sownqs dead easy to make the change.

Internal on painted steels. Not a clue where I got it from, was five years ago.

I used foil faced aerogel, easier to work with and stick down. I think I used double sided tape.

We (un)subtlety told the surveyor the valuation we needed. He did this on all bar one occasion.

My architect always said anything within the dimensions of a concrete block would probably be ok with planning.

It's easy. You can certify it yourself with an anerometer and a spreadsheet. I think there is an MVHR design sheet floating around the forum somewhere. Tl;Dr, make sure your duct runs are as short as possible and your diameters are as big as possible.

Depends on the valuation. The getting out of the ground stage is the most expensive part, but also adds the least value. You really want some walls built before you get the valuer out. Get as much money as you can at each stage. Our biggest regret is not drawing down more!!!

Bancroft had it well covered, my view as a self builder and as a project manager as a day job. Avoiding a main contractor and managing the build yourself will save you upto 30% of project cost. BUT... Getting trades will be tough. You take more responsibility and risk. It takes a LOT of time as you have to learn and do at the same time. It's much more satisfying. The key thing is to make sure roles, responsibilities etc are clearly defined. "However, a close friend, who I trust, is a self-employed carpenter and runs a carpentry/renovation business with his business partner. They do not normally operate in my area and they do not have the experience/capacity to take on the whole project, but they do have good experience working on renovation projects. My idea would be for him to take on the elements he is comfortable with and help me coordinate some other packages." I would absolutely not do this. Recipe for disaster. Grey lines. No cost control, you take all the risk. You'll fall out when something goes wrong. Much more to it than this but I've no time to say more right now. Something that you'll soon be familiar with 🤣

Ohhh don't even think about picking up that phone.

I just put a 22mm isolating valve on each of the manifolds. Not the end of the world.

I got stick on fish tank / brewing thermometers. Not the most precise but gives you a good idea of what's going on.

I agree that induction hobs are terrible for woks, but I've seen one of these in action in a restaurant and they are fantastic. Worth considering to save you a lot of hassle. https://www.nisbets.co.uk/buffalo-induction-wok/ja372

More likely a chemical reaction between the wet concrete and the boards.