Built a shed without permit

[Jack91]

So,
Ive built a 10x8x3.6m high (at sides) shed without a permit. Its way overbuilt, 150x50x4 beams, 12mm plates, m18 bolts, bolt cages in huge footings, 1.9 purlin etc.

Ive talked to an engineer and the process to rectify this seems hard and expensive, i also need a dispensation as im closer than a metre to boundary aswell.

Does anyone know approx what $ im looking at? Itll need to be drawn by a draftsman, signed off by an engineer, then go through council as far as i understand it.

Ive also got a 6x6 deck but i think thatll be pretty straightforward to get through. Im happy to take the sheets off that roof if i have to

Any help appreciated.