That's the way I'd go Hamish.
Good my head is hopefully screwed on properly

Hamish, I've literally just ripped out all the carpets and underlay from my house. It's rolled up in the shed at the minute and will be skipped in a couple of weeks when I get ashore again. I need to keep some for the loft but you'd be more than welcome to have as much as you need if you want to put some down in there?
All the best
Andy
Ooo may be handy, I'm not sure what i'm doing with the floor just yet. Was thinking of getting those foamy jigsaw things to line it as they are easy to clean and move about etc
Hamish, to your question:
I would leave a small gap between the insulation, on both sides.
The outside wall of the shed is not made 100% weather proof, same with floor. I rather lose a bit heat than having a mould problem.
For insulation I would use closed cell foam type styrofoam sheets. Easy to work with, and mice will not build nests in it.
I ade and insulated a shed like this in UK about 11 years ago, and it is still going strong according to my old neighbours.
Electrics I would place exposed.
Good advice that's my plan, I have plenty of space to leave a gap on both sides, and I definitely want to avoid damp/mould as much as possible as my workshop will be filled with leather