Yes, I'm afraid a total ban on hand baggage is sustanable. It's very easy to do, and much simpler for airport authorities.
No it is not. If you were capable of deductive reasoning, you would realize that the impact of this action will be politically unacceptable due to loss of tax revenues and extremely strong lobbying from the airlines and business.
This action is placing UK plc at a competitive disadvantage.
Therefore it is not sustainable.