Ford Fiesta Diesel Problems

You’re right; a cylinder head gasket shouldn’t just ‘let go’. Ask your dealer to request Ford to cover at least part of the cost of repairing your car. Even though the warranty has expired they still have an obligation under consumer laws to support the vehicle.

Your best course of action is to take it back and ask that it be fixed at their cost. It's all down to negotiation I'm afraid, but if they are reputable people they should come to the party.

It suggests there could be a loss of oil pressure, so don't drive it, instead take it to a mechanic to have it checked.