Insulating 3 car garage/shed

I'm looking for advice about insulating a shed that is big enough for 3 cars, there are 2 roller doors, there is already a basic kitchenette that I would also be replacing at some point.

I want to do this so that during summer I can put air con on in there and have people over. My house is not huge so I see this as a logical choice for extra living space. I won't be using it to store any vehicles as there is enough covered areas to house a couple of cars.

I have had a couple of builders come out and look at what I want to do but have never received a quote from anyone. The walls are plain metal walls.

m4cc4s Welcome to the forum
More info required & Photos help
Cheers

The Inside

I want to keep the roof area open. Ignore the contents in the area.


This is one of the ends, the projector screen will be going back on the wall



The back wall has power & data outlets and TVs will also be going back on this wall



The other end has a bench along the enter end, although it is a nice and sturdy bench I'm happy for it to be removed if required.



The other wall has the 2 roller doors, a hinged door and the kitchenette. These are going to remain.



A closer look at the bench




The outside


Front, with doors open


Left Side


Back (looking at putting a storage shed behind this one)


Right side


Front with the doors closed.

Hi m4cc4s

Thanks for the Photos
I recommend you insulate the walls & ceiling
Batten (600crts) out the frame and put up plasterboard?
Here's a quick breakdown of Materials & Labour
You can source the material prices online

Guesstimate
6x9x3 Shed
Volume 180m3 (No deductions made for content)
Wall Surface Area 94m2
Ceiling Surface Area 56m2
Battens Steel Top Hate 180 l/m
You may need to make deductions for Doors & Windows
Materials
R 3.5 Insulation Batts
10mm Plasterboard?
Labour 1+1
Top Hat Battens, Insulate & line
2 people 2 weeks work
Cheers

Here is a link to a pretty detailed video on insulating a garage, in Melbourne. Spray foam combined with conventional batts.
https://www.youtube.com/watch?v=fJGYchSx5SY