Overall it's only really cost me about £250, Excluding the cost of the decking.
My dad got me the shed for xmas which was about £600, I put £100 towards that.
£80 for insulation
Plastic membrane was free from work
Pallets were free from work
£45 for 1"x1" planks
£20 for sockets
Wiring, comsumer unit, MCBs, light switch all came from work.
I should have a nice little workshop out there once it's finished. Can't wait, I've put actual airsofting on hold for the last 3 months whilst this project is going on. Thanks for the kind words!