I don't.
I've never fitted a fused spur when fed off a lighting circuit and to be honest never seen one wired by anybody else with both a fused spur and a triple pole isolation switch.
So you are therefore failing to install it in compliance with the manufacturers instruction and therefore does not comply with BS7671.
I prefer to fit a 3A fused spur and isolator to this type of setup.
It has always been the way that I have been taught that the manufacturers instructions over-rule the IEE regs anyway.
As for the 17th edition, you will also need to look into providing RCD protection too.
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