Sort of but you would need a junction box or similar with the feed wiring removed from the ceiling rose as the ceiling rose would now pick up all it's supply from the isolator. I would also not bother with an indicator light on the isolator unless you really want a red neon glowing 24/7.
The 3 pole wiring diagram actually looks the simplest in the long run as you keep your existing lighting wiring and piggy back onto it in the ceiling rose to feed the fan and isolator.
Sort of but you would need a junction box or similar with the feed wiring removed from the ceiling rose as the ceiling rose would now pick up all it's supply from the isolator. I would also not bother with an indicator light on the isolator unless you really want a red neon glowing 24/7.
The 3 pole wiring diagram actually looks the simplest in the long run as you keep your existing lighting wiring and piggy back onto it in the ceiling rose to feed the fan and isolator.