yes the repossession of a property by the lender can be carried out at any time once you are in arrears with the mortgage.Bankruptcy is a seperate issue.
actually no, technically one month arrears is sufficient as you are in breach of the mortgage agreement.
That said, it has long been the case that if a lender applied to the court for repossession when there are less than 3 months arrears the court would deny the application.
Now of course good old Gordon has "instructed" lenders not to apply for repossession until the arrears are at least 3 months, and he gets slapped on the back when, as he well knew, the courts wouldn't have allowed such applications anyway!!!