@Ferdinand - yes the solar gain is worrying me. I agree we may have to consider shading (and have been wondering if we'd need to talk to planners about it).
The layout is evolving a little, too, as we do the construction drawings. A pocket door off the hall instead of hinged. Sacrificing half the utiility room space to put in a second downstairs loo if granny moves in and is exclusive user of loo No 1 (the extra space it could initially be a walk in larder).
The most unsettling issue is that our architect has revealed that in order to satisfy the roof insulation etc where the terrace over the family room is, there would have to be a step UP of about a foot between the master bedroom and the terrace. Never mentioned this before, and I'm pretty (very) unhappy about it. Looking for ways to make that go away at the moment (can be done but will cost lots).
Too much going on and far too many decisions to make. We need to get on with the garage rebuild, but also need enough info to put in building regs for the entire site before we start anything.
I'll start a thread about this building if that's OK, get it off the intro page. Hopefully it'll be interesting to a few people.
Thankyou for that tip @Nickfromwales