Stripe Invoicing has no monthly fee. Starter costs 0.4% of each paid invoice; Plus costs 0.5% and adds quotes. On top of that, Stripe's UK card processing applies: 1.5% + 20p on a standard UK card, 2.5% + 20p on a European card, 3.15% + 20p on an international one. Both plans give you a hosted invoice page, automatic email reminders and retries, a customer portal and reporting. Its UK pricing page doesn't mention deposits, part payments or Pay by Bank, and lists Bacs Direct Debit at 1% capped at £4. You set up and run the Stripe account and dashboard yourself.
WorkPaid has no monthly fee either. Sending quotes and invoices is free. When a customer pays, WorkPaid takes 2.5%, capped at £500 a quote, and you can pass that on to the customer. Processing is the same Stripe rate, 1.5% + 20p on a UK card, or 0.5% + 20p (capped at £5) when the customer pays by bank. Your Stripe account is created for you from inside WorkPaid, and you never need the Stripe dashboard.