Well after some hot sunny days and finally all the plumbing parts arrived, I have my bog filter setup and running. Using some spare solvent weld piping I had, constructed and glued in with slot cuts underneath.
Took an afternoon to clean the 10mm gravel stones as covered in mud and silt. Added to container and fired up. Some sediment still present but not enough to do any harm.
Added some plant pots from pond to bog just to see how it'll look as well as ordering some additional pond plants I'll add to the bog.
The clean out pipe will be cut down to size as a tad too high so once spare part arrives, clean out screw on will be same level as where output water is.
The winner is I still have 5 fingers in each hand as I'm always a disaster when it comes to DIY