Unless you have two written warnings, and you are bing straight up with us, then what has happened wasn’t “gross misconduct”. Hitting someone, vebally abusing, bullying , racist behaviour is gross misconduct.
Dig out your contract now , and read throught it. If you were really working 10 hours with only a 30 minutes break, then take them to court.
But you have to be honest about you role in this. Was this mis-ordering the only reason.
Go for unfair dismissal – you will win the case and they will probably want to settle out of court.
BTW, if you were having to work all these hours, what are they going to do now they have got rid of you?