I am going through this process right now in an attempted to use a prefab timber frame extension to an existing home (ca. 1800 thatched cottage). We actually tried to get a Dutch thatcher incidentally but she was too busy! A similar house would be completely illegal to build now (internal space is ~600 square feet) but ironically it's illegal to demolish too (protected structure)

The homes around here are mostly, to be honest, pretty ugly concrete block pebble-dashed bungalows. I don't mind that because hey, to each their own, but saying that a home which looks like a log cabin doesn't match the local aesthetic so we should keep all houses in this style is frustrating.

I do wonder if planners have a kneejerk reaction to anything cheap since a huge amount of public policy is specifically designed to keep housing expensive (or "preserve home values" if you're so inclined) The bias towards slow, inefficient, on-site building is hard to understand.

There have been many projects in the eighties that reserved areas of neighborhoods which dropped most building regulations as you describe them here, including one in Emmen, where I was born. The results are not pretty: garish, impractical, unconnected with the surroundings. Although, perhaps amenable to the first owner, once the buildings are listed for sale, few seem to appreciate the builders unique taste. Furthermore, even though some of the houses are nicely built, many of them are just out of place: a Mediterranean house next to a Scandinavian, followed by a ‘large wooden shed’.

Newer projects have more appeal, where a larger group of families work together to form a connected architectural plan, often themed with energy neutral constraints. Perhaps that could be an option for you as well?

Finally, if you buy a large plot of land (villa style) you can do almost anything you like, especially because you are probably influential and able to convince the local government of your plans.

If you could design your new building so that it was invisible to everyone but you, there would be no need for these mind of regs. Unfortunately every built structure haas an impact on those around it.