The building regulations are quite clear about how they apply to
conservatories as new build, but not so clear as conversions.

A conservatory has been in place for a number of years, no problems
structurally. But if minor changes are made (which in themselves would
not require permission) how would the building regs come to apply?

ie is permission needed to carry out the minor changes, or is
permission needed on the basis of 'converting' the conservatory?

The roof should be more than 75% transluscent for it to be classed as
a conservatory, but how will the building regs apply if the roof is
changed so that it is less than 75% translucent?
What does the room become? Does it become an 'habitable room' even
though it will not be used like other rooms? Does it become a bedroom
or a lounge, could it be a store or a hallway - who decides?

I'm particularly intrested in the structural side of what will be
required. If it is to be classed as an extension, then normally an
extensions' foundations would be typically 1 metre deep, but a
conservatory's only say 500mm. So as part of any conversion work,
would the BCO insist on underpinning? Would calculations be required
for the [existing] roof structure, as it is not covered in the
building regs and thus 'non-standard'.

The gist is, how far can/would a BCO be expected to go in terms of
what work would be required?

dg