Defence chemical, biological, radiological and nuclear centre had or may still even have a Dominie T.1, which would be a prime candidate for the smallish airliner you slept in. There is also a Hercules fuselage or flight deck, depending on your source.
CBRNC is at Winternorne Gunner near to Boscombe Down Airfield and I can see nothing on Google Earth
Pontrilas Training Area
Never came across any 'Airliner' sized aircraft on Salsbury plain, but things change all the time.
Special Forces train for assaulting hijacked aircraft using a mock up of a passenger airliner at the training ground at Pontrilas, Herefordshire.
Internal hangers can also be configured to emulate the interior of airliners.
Frequent exercises involving real-world aircraft (usually provided by British Airways) take place, complete with role-playing terrorists and hostages.