MATZ - Call the ATSU and ask for a Traffic Service and tell them you are routing via their overhead or route. Example "Boscombe Radar N123 from A to B via your overhead, 5 miles west FL50 request traffic service"
DA - Call the ATSU nearest / responsible or London Info (scottish oop North) and ask them the status of the DA...Ex "N123 from A to B via C 5 miles west of D 5000, request status of danger area Delta 123".
If they say it is cold, or inactive then bob's your uncle you can do whatever you want. If it is active then I tend to avoid rather than trying to get a crossing service.