The security tight, but immigration control is very lax when you depart, so should not be a problem (at least Heathrow lar). They are probably very happy you leave, and just black list you.

However, I think it is not easy to return on emergency la. Your rental deposit everything, need to settle one leh. If not you lose deposit etc. Rugi besar. Withdrawal of money etc is not efficient here. Now even more mah fan, cos they takut people sell pound down. My friend graduated and wanted to transfer her savings out. Kena question by bank officers one whole hour. so many processes. Even legally here also mah fan. If your relative’s kids’ jump aeroplane, better give more notice. I dun know what they have to do- may be more?