If a Charge for Payment has been served, they can try and arrest your wages , providing of course they know where you are employed.
However, as you say, you are on a zero hour contract, so how much you earn can fluctuate from week to week, so whether an arrestment will succeed will depend on your earnings.
If you earn less than £113.68 per week (take home) they cannot arrest your wages. If you earn over that amount they can take £4 or 19% of your earnings above £113.68 per week. This is up until you earn more than £410.90, then the amounts change.
Monthly the minimum that is protected is £494.01 per month.