Thanks!
@davyboi - if I put some weedstop fabric and then some gravel, would that help? Hadn't thought about it being draughty like that.
I cant reallycut away any of the decking, its levelling a slope and built up quite high :( (the greenhouse would look like a subterranean cold frame ;D )
@palmski yes, thought grow bags and staging for seeds and plants etc. Him-Indoors is now looking thrilled at holes in the decking ;D
Next question....looking at the polycarbonate greenhouses they all seem opaque, does that not stop light getting through or does it help if its too bright and sunny?