I don't know why Screwfix still mention copper tube to Table X in their blurb as this only applied to BS 2871 which has been superseded by EN 1057 which does not use the Table classification.
You don't say what material the tray is and whether it is installed on a suspended or solid floor. TBH I would be trying to find out why the tray sank in the first place rather than just fill the gap (which could get bigger) and then try to rectify the sinking rather than bodge the job.
It certainly is. I spent the first 14 years of my working life producing detailed mechanical services drawings and plans for all sorts of projects on a similar board to the opening post. Still got all the bits 'n bobs, pens and stencils. I tried to move over to CAD but always reverted to the...
Perhaps you need to build it on something like those concrete mushrooms that farmers used to install to prevent vermin getting into the barns/grain store! :cool:
I'm surprised, looking at the agents listing pics, that they got away with the uPVC gutters/pipework particularly on the front elevation.
Perhaps there are different rools for 'oop north as opposed to the ones in Surrey/Sussex that I was involved with.