CCJ: "You may get a county court judgment (CCJ) or high court judgment if someone takes court action against you (saying you owe them money) and you do not respond." https://www.gov.uk/county-court-judgments-ccj-for-debt

In which case they'll likely get an attachment of earnings order and take the owed straight from anyone not paying anyway, silly muggles.

County court judgement for anyone wondering

In Canada, they'd probably just freeze (hah!) your bank account and take the payment from there.