sealing up a shed/weather proofing tips? shed upgrades?

[Hell Cat]

Hi.

Just wondering if anyone here has had experience sealing up their sheds from mice/creepy crawlys/weather?

My shed is a 6x9 stratco, the outer sheet metal over hangs against the slab, fortunately I have never had any water leak into the shed (Only when pressure washing near the doors.

I would like to try to seal the gap between the slab and sheet to prevent dirt/mice etc coming in through the gap, I unwrapped my engine that was has been tucked in the corner to discover mice had made a nest.
Im also hoping to try to seal up the top where the roof meets the walls.

Im (reluctantly) letting the mrs have one bay of the shed to set up her sewing equipment because she's starting her sewing business back up again.
The fabrics are quite expensive so I'd like to prevent any un-necessary damage....


After that I will cover the floor with lino or the industiral resin/flake coating, I have been
thinking about insulating the shed also and putting up smooth walls inside to make it a bit more comfortable in summer and also look better on the inside. Ply/chipboard/gyrprock? Not sure how it would hold up as it expands/contracts with the weather.

Overhead wall storage? Have you done it?