A calculator can estimate repayments, but it cannot predict exactly what your lender will do if you miss one. You may face charges, interest continuing to build and a missed-payment marker on your credit file, while repeated missed payments could lead to arrears or a default being recorded. Contact the lender as soon as possible, explain your situation and ask whether a temporary arrangement is available. If you are struggling with several debts, consider free help from MoneyHelper or a UK debt charity.