England: signed off work until end of March but need to care for sick relative overseas. Work have scheduled a welfare call. How do I approach this please?

I'm flying on Wednesday, the call is on Thursday. I'm at a complete loss. My mum was an emergency admission and there's no one else to care for her (social care packages non existent for those of low means). Will they sack me? Will they ask me to resign? I'm very concerned. Any advice appreciated.