The hall is the private property of the school.
So what you’re asking is similar to asking whether you have a legal right to use a neighbour’s private swimming pool when they’re not using it.
The answer is “no”. But there’s no law about you asking the school for permission to ise their room/hall after school hours and if they agree you can expect to have to pay for the privilege: that payment covers liability insurance, cleaning, overtime for the caretaker to come and check and then lock up, plus a plain straightforward fee for using the room/hall which will go towards school funds.
Where schools do allow such activities, they are usually limited to the school hall instead of classrooms. That’s because classrooms are likely to contain personal property of the teacher and pupils, and also confidential information about pupils, even if it’s only their names. So classrooms are usually locked after the daily cleaners have finished inside them.