Some do, but many (most?) have younger siblings so still can't.
If it is your youngest, or only dc, and you can get tme of work yourselves, then it is nice to go when it is cheaper.
Remember to find out the date of 'Prom' if they want to go, to.
Increasingly 6th forms have 'Applicant Days' after GCSEs too - I mean, you can miss them but some dc don't want to.
Then, there is fitting in NCS, and there is finding work