Yes. From 5pm on 31 December 2020 you must wear a fitted face mask when you are in public indoor spaces unless you have a lawful reason not to.
There are a number of lawful excuses for not wearing a face mask in settings where a face mask is mandatory, such as illness or disability. Other reasons a person may choose not to wear a mask include where the person is:
under 12 years of age a student at a primary school or outside school hours care in the process of being married a professional sportsperson when training or competing engaged in any strenuous physical exercise receiving a service where it is not reasonably practicable to receive that service wearing a face covering.
full list of exemptions