V-Flyer

I have a flight booked to Manila with China Southern airline, flying via Guangzhou, China.
If, due to the present Coronavirus situation, my flight is cancelled will China Southern be liable under EU261 regulations and will I be able to ask for a rerouting to Manila with a different airline that does not go via China?.
I am not due to fly for another 4 weeks, but I want to consider having a "plan B" in place to ensure I can get to Manila.
Thanks in advance,
Tim.

Doubt EU261 would apply as it's beyond their control

Not quite true: you are not entitled to compensation if the delay or cancellation is beyond the airline’s control, but you are entitled to duty of care and to be re-routed or refunded, whatever the cause.

So even if China Southern cancels its UK flights it still has to get the OP to their final destination, if that’s what they want. That doesn’t mean the OP can demand whatever re-routing they want, but the airline’s unlikely to refuse a request for a reasonable alternative.