From the official gov website:
Businesses selling food or drink (including cafes, bars, pubs and restaurants), social clubs, casinos, bowling alleys, amusement arcades (and other indoor leisure centres or facilities), funfairs, theme parks, adventure parks and activities, and bingo halls, must be closed between 10pm and 5am. This will include takeaways but delivery services can continue after 10pm (from 24 September).
Theatre and cinema performances are the only two exempt and can run over the 10pm curfew, but the bars/kiosks must be shut down by then.
So yes, guests will have to be out of the park by 10pm, so it will affect ride/maze close times; as they will probably have to shut the queues earlier due to how popular the event is.