@TerryE Thank you for the good advice. Indeed - having spent the last few months trawling buildhub, I've realised there is almost an infinite amount of things to learn about and get our heads around - from bats to build methods to thermal design! The only sure thing about this project is that it'll be a very steep learning curve!!! Your point about a partnership is a good one - my partner is more about the big picture, whilst I am extremely detail-oriented (perhaps obsessively so) so we will be sharing the load in a way that reflects our personalities...
We are getting an architect as 1) our build is a pretty major one for us, 2) we've never done a build before and 3) we do not have the time or (more importantly) skills to do what other buildhubbers have done and design their own! To your point about brief and specs, we've spent the Christmas period really nailing down our "wishlist" and have come up with a detailed (9-page!) brief for the architect and landscape designers to work from - this covers our aspirations for the property, sizes and spaces of the rooms we want, how we intend to use each space, etc. However, in terms of design, apart from knowing that we want a traditional stone house (such as yours) being in the AONB, we are happy to be led by the designers as to shape, form, orientation and aesthetics. Having spoken to various architects, I realise that where they can really add value is helping to design a property that sits well in the context of the landscape and surroundings - which is so important for us as we are in a semi-rural area overlooking the valleys. (Though we are very much avid Pinteresters so we will most definitely be providing our input when concept designs are produced.)
As we live in London and the property is in the Cotswolds, we will be hiring a PM, or (less likely) having our architect manage the build. My thinking is that if we do go for an MBC type build, we would only bring on a PM after the frame is up to help manage the trades. Perhaps we should start speaking to PMs now to find out their availabilities and experiences with managing timber frame builds - I do have a shortlist of PMs but have yet to contact anyone.
In terms of broad spec - finishes will be mid to high-end for the house, and mid-range for our cottage. We will need to look at energy design more closely to figure out what is affordable/realistic and I'm now doing my homework about all things energy/insulation/heat loss/renewables and will have a play with Jeremy's heat loss calculator once we have a concept design. We will be following Passivhaus principles but not building to Passivhaus standards. We might have a go at district heating for the commercial RHI as we will have the house, cottage and a garage flat - though this is just broad strokes thinking at the moment and I will need to do the calcs for sure.
Re planning, I have stalked the LPA website extensively and compiled a summary spreadsheet of replacement dwelling cases and applications for large extensions - noting why some have been permitted or refused. Currently, this is the biggest unknown for us and I'm doing as much research as I can on planning processes and timelines in order to manage expectations. We do also have a planning consultant onboard who can hopefully help us to navigate this murky AND subjective process!
Back to more blog reading now - many more questions to come!