My eldest son used to work from home, but the business grew, so we bought his accountants old offices. I was a terraced house with business use already, so we installed a modern shop front door and window. Then to the inside, after the plasterer had boarded and skimmed, I built a raised platform across the back and using reclaimed timber battens and new floorboards to hide cables.
Onto this platform were added three Ikea Expedit units to give flexible, flexible storage spaces, the side facing into the shop was covered with reclaimed MDF sheeting from archive shelving already in the building. This was then clad in random planks of pallet wood that had been sanded and waxed beforehand, a cheap nail gun from Screwfix worked wonders.
The old fireplace had a reclaimed steel beam inserted and waxed; and then old scaffold boards were cut to fit the stepped space, held to the wall by coach screws counterbored and heavy duty wall plugs. The metal straps are from the ends of the scaffold boards, straightened out and polished. It was all completed by me in August 2014 and has not needed any further treatment other than an occasional wipe down.