I think he does not have the BGB, or can"t read it, as for have not installed SWA before what did he learn at collage how to plum in a washing machine, as for RCD why not put one in the centre of SWA as well as both end as this would not help at all but might look good
But I think a better idea would be to just get some 2.5 twin/earth as it"s a lot easy to make off than SWA and then just IT it and put a sticker in flowerbed.
JOB DONE no need to test as it will be OOK in the end and we will not have to put up OPs like this,