It's interesting that increasing numbers of conservatory specialists are now providing specific garden office models. The Kent Conservatory Company has a special garden lodge section on its web site which can be built on a simple concrete base. Here's how they describe it:
"Using standard building construction materials they are designed to be durable and attractive, blending in with surrounding architectural buildings. Internally we can offer a full range of floor, wall and ceiling finishes to make your new room complete in every way."An example is pictured above.