you`re staying with your friends in Britain You were planning to go to cinema together this afternoon but your plans have changed.Leave a note for your friends
1)Apologise for the change
2)Explain why you can`t go
3) Suggest another day

Hi Tom,I am really sorry but I'm afraid my plans for today have changed unexpectedy. I have a little family emergency, and I need to rush to the hospital to stay with my sister. I still want to see the film, so I would like to suggest going to the cinema on Saturday.Please let me know whether it suits you or not.Cheers,(Your name)