Some people here do seem to get away with illegal building, but beware.
Spotter planes are sent out and take note of bits added on to so called sheds.
Only last week a house near here was demolished after the owners had been warned and told not to carry on with the building work.
You mentioned in a previous post I am sure, about being on the edge of a Park with forest area!
A few years ago a couple built their dream house on the edge of a Park. They were told not to, but they carried on
only to loose everything.
I am sure your solicitor has advised you not to go ahead?