Hello Brian,
From the NA -
"H Flight, 1 Anti-Aircraft Co-operation Unit, Biggin Hill; moved to Gosport and transferred to 2 AACU 20 September 1939; transferred back 11 October 1940".
Have you search the RAF Commands Forum posts and database ?
A quick look gave up the following -
http://www.rafcommands.com/database/...=&qmem=&qdate=
2 AACU
http://www.rafcommands.com/database/...AACU&crdb=Henk
Alex