To answer the OP, the same one I've given all along(which would require a change in the law, both international and domestic): For UK citizens internment without trial for a period of 6 months, whilst incommunicado. No Koran, no prayer meetings, no association, no visitors. For those not born in he UK, immediate deportation to their country of origin.
These people are are on lists and 'on the radar' for good reason, therefore it's only right and proper that such draconian action be taken to protect innocent UK citizens.