Nightclubs are not included within the use class and would normally be Sui Generis.
This is a relatively new class, in England, created in a change to the use classes order, splitting the original A3 use into three separate uses, A3, A5 and A4 Use Class.
While this currently does not apply in Wales, recent consultations have sought a similar splitting of the A3 use to create effectively an A4 Use Class like England.