[Closed] New House = New Shed build time

Just bought a new house and I am delighted to find that I can fit a shed in the garden up to 10'x 8'. It's a corner plot which means there is a perfect area for a shed at the bottom of the garden, due to the way the other gardens intersect.

I could buy an off the shelf cheapo shed, plonk it on some slabs and be done with it. However the ideal would be that this is a small workshop for bike tinkering etc. So I'm looking for something a bit more than a shed but not quite a full on garden room, however insulated walls and ceiling would be good. Bikes are planned to be stored in a more secure and smaller Asgard metal shed, including a ground anchor. This will also serve as a stop gap as it can be easy thrown up and bikes secured in it.

Firstly, the base. The proposed shed area is at the bottom of the garden. The ground slopes gently down from the house towards this area. So I am thinking that if I go for a solid concrete base I will have damp and water pooling issues. Therefore I think the shed should be slightly raised off the ground on concrete blocks/pillars to allow water to run off underneath it. Good idea?

The shed itself. Is there anyone near to central belt Scotland who manufacturers or sells decent sheds/workshops that can be or are insulated?
The other option is build it myself. Thinking stud work with OSB on outside, then wrapped in Tyvek or similar, batons and cladding. In fact I think the walls are the easy bit. Not too sure on the roof yet. Any pointers would be great. Also I suppose the shed doesn't have to be wood!

Power. I have an outside socket on the house and plan to run an armoured cable from it to the shed to provide it with electricity. I think the outdoor socket has it's own breaker. Will need to check and also uprate if necessary.

Budget, less than £1k, the lower the better.

Would appreciate any pointers!