ETC

Having a fan light above the door is no different that the windows already shown to the LHS - just move the timber lintels shown above the door to directly under the wall plate. I’m presuming this is a timber frame and the lintels have all been designed by a timber frame specialist? If you are having an external masonry skin then you should be using a Keystone (OOEAA) L-shaped lintel on the outside.

Add an extra 200mm of mineral wool insulation. Make sure you don’t block the eaves ventilation. Fit an insect mesh along the eaves - if not already fitted. If converting to a warm roof insulate along and below the rafter line and the new ceiling plane but make sure the eaves ventilation is not blocked and that ventilation can travel from eaves to eaves.

Firstly - if the window is at first floor level only and the height of the opening is less than 800mm above the floor level then the glass needs to be safety glass to act as guarding. Secondly - if the window can also open more than 100mm then then window needs guarding so that someone cannot fall out. The solution is simple - fit a non-lockable restrictor stay. Not one with a lock as shown by a previous poster. These do not comply. Fit something like this: https://www.amazon.co.uk/Window-Restrictor-Hook-Safety-Handed/dp/B00D9190BM/ref=asc_df_B00D9190BM/?tag=googshopuk-21&linkCode=df0&hvadid=214440742293&hvpos=&hvnetw=g&hvrand=10205647162280157693&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1007277&hvtargid=pla-421872985378&psc=1

My solution. Elevation to follow.

Sell the garage to your neighbour.

Lazy. Shocking. Disappointing.

Yes. Only extras should be SE, M&E and QS. If he can’t do it go to someone who can.

Completely agree.

What is your outside skin made from. If it’s brick or rendered block you won’t have an issue with FR to the timber frame. You will be limited to the extent of glazing though depending on the distance of the external walls to the boundaries.

Get your SE to specify some angles and SHS posts as lintels. The loads won’t be massive so the section sizes could be quite small. Alternatively get Keystone to design you something.

The garage will unheated so the wall between the garage and the dwelling needs perimeter insulation on the dwelling side.

External walls only but would do the party wall too. Not needed between heated spaces.

Insulated screed.

Sounds about right. Fire doors not needed in a two storey dwelling (except the door between an attached garage and the dwelling) as long as EEWs are provided to all habitable rooms and direct access to the stairwell is provided. See Approved Document B. Other caveats explained.

Good point - however the onus will be on the architect to check that the information he is supplied with is accurate. I also suspect that the survey was carried out by the architect and not a third party - I could be wrong but for a (small) domestic project like this I would imagine that the survey was carried out in house rather than sub-contracted to a third party. OP suggests that the elevations and sections did not tie up - amateur mistake. Just my opinion.

Difficult one - but I don’t necessarily agree with CharlieKLP. No - you should never scale off a drawings for anything and should always use site or figured dimensions. However my personal opinion is that if you were supplied with inaccurate drawings by your architect then he should accept some responsibility for the mistake - irrespective of the drawings being dimensioned or not or any caveats placed on the drawings. Speak to him and tell him how you feel. Am I correct in saying that the section is new works and the gable behind is existing. If this is the case then the solution your architect came up with looks quite contrived. It would have been better to extend the existing roof over the new extension and to forget about flashing - just my opinion.

Turf?

Why do you want to thermally insulate between two heated spaces?

I think you’ll have to accept that in this climate the wood cladding will turn a different colour over time. I don’t think plastic alternatives would look right.

Burnt larch?

Slate?