For a long time now, businesses have had the legal right to charge interest (and, in fact, compensation and costs) when invoices are paid late, at 8% above the Bank of England base rate. In real life, you very rarely see the right exercised, maybe because people don't know they can do it, maybe because for small invoices paid a bit late it's not that much money, but probably mostly because the supplier doesn't want to antagonise a client and colour the relationship.
But actually businesses that pay invoices late sometimes don't seem too upset when they're legitimately charged interest - they see paying invoices late as a perfectly normal part of business, and the interest as a perfectly normal consequence. We remember one or two clients who've been very reluctant to charge interest to recalcitrant customers, who eventually found that the customers were quite content to pay.
There's a useful calculator you can use here to work out how much interest you could charge on an invoice that's been paid late, with some helpful wording for the invoice:
https://www.smallbusinesscommissioner.gov.uk/deal-with-an-unpaid-invoice/how-to-chase-an-unpaid-invoice/interest-calculator/
Obviously, maybe you've got a customer who really will be aggravated if you charge interest, and it won't be worth it. But small businesses should probably exercise the right to do it more often than they do.