Just NATO standardised Squadron callsigns.
NATO Squadron callsigns are allocated in accordance with NATO Publication ACP 100 - Allied Call Sign and Address Group System–Instructions and Assignments. There is a UK Supplement Annex to ACP 100 which details all UK squadron allocations and also special tactical callsigns like the alpha-numeric ones.
You could write to MOD and request it under Freedom of Information Act regulations
www.mod.uk/DefenceInternet/FreedomOfInformationThey may not release the whole document to protect the special and tactical callsigns under national security caveats, but should provide a redacted version which would include the daily used Squadron callsigns.
Regards