Roundtuit

I guess they can only really do generic, but the conclusion looks fairly definitive to me I'm afraid: it's ill-advised.

That's not generally the case. Whilst no one wants standing water on crops for any length of time, run-off from agricultural land is avoided as it takes soil with it and causes erosion. In this case however, 'public field' suggests perhaps a permanent grass recreation area?

Yep, that’s one massive cat litter tray! As @Nickfromwales, I'd be looking at rubber mats in critical areas.

I'd suggest that building a house is significantly more upheaval and stressful than choosing one that's already built and letting the removal men work their magic. Don't let that put you off, but make your choices from an informed position!

Assuming this is just rain water off a relatively small area, is a soakaway a less expensive option? If not, then I'd say your proposal sounds reasonable; give them notice and just do it.

No idea what you're planning in terms of space heating/DHW, but as mentioned earlier, be careful not to underestimate the area needed for plant. I'd maybe get a kitchen designer to look at getting best utility out of that area; the current design looks a bit awkward tbh, and you need to plan drainage runs. No dishwasher?

In my experience, no-one checks. I've made a few tweaks to locations and species, although have generally followed the 'spirit' of the landscaping plan. Planting was supposed to be completed in the first season after occupation, which also didn't happen. If I were you, unless it's a pre-commencement condition, I think I'd put planting decisions on the back burner for now. As an observation on the current plan, I wouldn't worry about the trees either side of the drive. I'd suggest that they won't be big enough to significantly impact visibility for a start, and when they mature, you'll be looking under the canopy not through it.

To remove laitence; the dodgy weak surface layer.

If you've had some sun today the immersion will have heated the tank to a higher temp than the ashp would. I think I'd stick it back in and wait for it to stabilise and see what happens. You could always run some hot water off first to cool the tank if the high reading worries you.

I like the look of galvanised. It's one of the most commented-on aspects of our build, strangely...

Really?! If their activities have the potential to cause harm or damage to your property I think it's an entirely reasonable question.

If it's still 'stabilising' I don't think you'll stop it, but it's unlikely to impact on structural integrity. Maybe just find a filler with a reasonable colour match.

This. Led strip in an aluminium profile with diffuser, cut to length.

Maybe invest in one or two 6m lengths and install them mid span at the same height as the structural walls, just as a temporary measure to sit the joists on whilst you bolt them?

I'm guessing the sistering is to gain a bit of head room rather than use deeper joists? What size joists are we talking? I have no expertise, but it doesn't look like a very elegant solution; any chance of getting a steel joist in there to split the span?