How much is exempt from PP?

Lex Luthor wrote:

I've been reading thro the CoCo pamphlet on what sq. meterage is exempt from PP and the figure 40 sqm is mentioned.

Does this figure mean total extensions/garages built at the back or side or are garages/fixed sheds classed seperate?

the way i read it is that lets assume all ur existing stuff has PP.

Then u add a garden shed say 20sq meters, since less than 40 no prob, no PP required.
The suppose u want to add a 15m sq conservatory, u say 15 + 20 <40 ok.
They say not ok as they only allow 1 "thing" with no PP.

So u can do 1 "thing" up to 40 without PP

Everything is included in the 40. I dont know about wooden garden shed as opposed to Brick and motor jobs