They must not enter without either, your permission or a Court Order.
Remember, though, that the law states "Let him who go to Court goes with clean hands" - only you know whether this gives you a defence - EG check out whether any Loan agreement was "properly executed" as required by law ie properly documented - check this out with your local CAB - if it wasn't, you have a good defence.
Good Luck
Storyjohn
Bailiffs - do you have to let them in?
Can they force an entry?
How do you stop them coming?
What sneaky tricks do they use?