All grown up

Tomorrow is E's last day at primary school, so tonight it's the p7s leaving Ceiliah which E point blank refuses to go to because he will have to dance. I have tried everything to persuade him to go, the last time he will be together with his class. The real reason he doesn't want to go is because he has football training with Morton!!
I could force him to go to the school Ceiliah, but what would that achieve? Is it worth the fight and argument?