Am in the process of converting a single-brick
outhouse-extension-type-thing into a kitchen, and to bring it up to
habitable standard I'm erecting a timber frame on the inside, so the
overall wall construction will be (from the outside): 4" brick, 1" air
gap, 2" Kingspan insulation (within the 2"-deep timber frame); 12mm
plasterboard/skim - this has been approved by the BCO.

The studs are being nailed to horizontal timbers on the floor and
ceiling, ie they aren't in contact with the brick wall at all, so no way
for damp to penetrate (as the BCO specified). However, I'm scratching
my head over how to fix one bit. There is a uPVC door fitted into the
brick wall, and immediately to the right of it there's a window, with no
intervening brickwork - ie the 'hole' in the brick wall is 'P' shaped:

__________________
| | |
| door | window |
| | |
| |________|
| |*
| |
| |
|________|


How do I support the studwork at the bottom left(*) of the window, given
that at that point I can't extend the stud vertically to the ceiling?
I'm presuming it will have to be fixed to the brickwork, but how? If I
interpose a length of DPC membrane between brick and timber, I'll still
have to breach that by putting screws through it.

I'm also not sure how you 'close the cavity' around doors and windows
with a wall construction like this, but that's a question for the future!

Thanks
David