Mortgage brokers have warned that many prospective buyers could have forgotten about the substantial tax cliff edge Britons may be bracing for the October Budget, which Prime Minister Keir Starmer has warned will be “painful”, but there’s already bad news for home-buyers on the horizon. A stamp duty cliff edge falls on April 1 next year, meaning buyers who purchase a property after this cut-off face paying thousands of pounds more in tax than they would if they completed the purchase in the days prior. Prospective first-time buyers could have to fork out an additional £6,250, a mortgage broker…