If they take place in front of an audience or spectators with the purpose of entertaining them and they are not one of the exemptions. The list of regulated entertainment can be modified by the Secretary of State by delegated legislation (and the first review of the list is proposed by the government between six and 12 months after the end of the transition phase).
These activities are defined as:

Performance of a play
A performance of any dramatic piece, whether involving improvisation or not, given wholly or in part by one or more persons actually present and performing in which most of what is done by the performers involves the playing of a role by way of speech, singing or action. This includes rehearsals

Exhibition of a film
Any exhibition of moving pictures except for

Product demonstrations
Advertisements for goods and services
Films providing information, education or instruction
Films forming part of an exhibit in a museum or art gallery
Simultaneous reception and playing of television broadcasts

Indoor sporting event
Any contest, exhibition or display of sport (which is defined as any game in which physical skill is the predominant factor or any form of physical recreation which is also engaged in for purposes of competition or display) taking place wholly inside a building (which is defined as any roofed structure, apart from those with opening roofs, and includes vehicles, vessels and movable structures) at which spectators are accommodated wholly within that building.

Boxing or wrestling entertainment
Any contest, exhibition or display of boxing or wrestling

Performance of live music
Performance of any vocal or instrumental music or any combination of the two. Music is not regarded as a performance of live music provided it is incidental to some other activity that is not itself regulated entertainment

Playing recorded music
Any playing recorded music unless it is incidental to some other activity that is not itself regulated entertainment

Performance of dance
Any performance of dance

Exemptions

Entertainment or facilities for the purposes of, or incidental to, religious meetings or services or at places of public religious worship.
Entertainment at garden fetes, or functions or events of a similar character, provided the proceeds are not for private gain.
Morris dancing and other dancing of a similar nature.
Entertainment or entertainment facilities on a moving vehicle when the vehicle is not permanently or temporarily parked.