David, can i be 1st to make a sugestion, build pillars of concrete blocks, put timbers accross and put the shed on top. This means you've got a good air flow underneath but more importantly the loft will be high enough to prevent mice and rats being able to live under the shed!
Lenut, if Joe or anybody else is able to do it then great!
Maybe David would like to write his own story and findings as it may have a better perspective coming from a total non fancier?
Phil