Sprout Up is a garden design, maintenance and advice service in south London run by former BBC television production manager (including Top Gear and various documentaries) Seonaid Royall. She works in a Garden Affairs flat roof model garden office with double doors and two long windows to the front. There is a nice Q&A with her on the site but here's a snippet to whet your appetite:
What made you decide to choose a garden room for your business?
When I set up my business I wanted to spend time getting to know my clients and their requirements so I could offer exactly what they needed. Expanding fast into an office space with rental fees wasn’t a sensible option. The garden room gave me the flexibility to grow successfully without paying overheads, while staying close to my family.