An agreement in principle is an indication of how much a lender might be prepared to lend, based on the information you provide and an initial credit check. It is not a formal mortgage offer or a guarantee that your application will be accepted. The lender will still assess your income, spending, debts, credit history and the property before making a final decision, which may include a valuation. Check whether obtaining one involves a hard credit search, and consider using an FCA-authorised lender or mortgage broker if you need guidance.