Posted: 28/09/2013 at 17:02
Hi Martin and Welcome
By my calculations (not always reliable I concede) you need about 7 tons of screened topsoil at between £20 - £40 per ton depending on quality, plus delivery - it'll come in Big Bags and you'll have to barrow it to where you want it.
Yes, you'll need to protect your fence from rotting - the best way would be to refence using concrete gravel boards at the base.
This is going to be a big and quite expensive job - there are other ways to diferentiate the garden from the patio - what about a bricked raised bed?
You'd have to have some sort of brick edging if you raised the garden anyway.
We're training an espalier pear a bit like a fence between our terrace and the garden.