Use a dark brown as the base coat, and dry brush a terracotta - Revell Reddish Brown is a good 1 to use. Paint the odd brick in dark tones of brown, some dark 'purple' like iron brick, then lightly dry brush with an ocher. Weather using inks and washes if your looking for a sooty look.
For Stone, work from a mid brown - like Humbrols old Dark Earth, use an ochre or a 'warm grey' then pick out the 'brick/stone' and light drybrush of beige... again soot as needed.
Not all of Victorian England suffered from dark satanic mills... its when coal started to be used for electricity production at the end of the 1880s and early 20th century the soot really built up.
There are and were timber - lap board buildings in London, however very rare as after the fire of London in 1666 they banned wooden construction. Wood was used as they needed to build quickly, but they were replaced with brick. The clapboard buildings near the Thames survived because they were close to the river. Newer buildings are rough brickwork covered in planks.
I have a look at facebook for marchattack, scroll through the pictures to see painted Gaslamp stuff.