Roland,
I think your suggestion about visiting AHB is favourite to find the answer to this question. However, comma....
Just because the RNAS was absorbed into the RAF in April 1918, it does not mean the Admiralty relinquished its role as Rigid Airship operator. The last military flight before all airship operations came under the Imperial Airship Scheme took place in 1919
AFAIK. I believe the RAF may have provided some manpower and airfield facilities after April 1918 but the Admiralty continued as the owner operator and hence, the RAF has never owned/had/operated/flown/whatever a rigid airship. That's my story and it needs to be disproved before I hand over the beer.