Should the power have to be cut off (which msy be for up to two days) the BBC will be using Radio 2 & Radio 4 FM/LW to broadcast emergency announcements and advice:
https://www.google.com/amp/s/amp.the...nter-blackouts
My worry is for those on VOIP landlines as they may need to contact someone in an emergency after the battery has run out.
Mobile phones, ATM's, traffic lights etc may all stop working.