BD,
TA in the traditional sense has all but folded now so that avenue is closed. Further, a requirement prior to serving in the TA in the flying role is to have been awarded a flying badge ie RN, Army or RAF wings. There is a small number of reservist "pool" pilots but I am certain this is only open to former Army pilots who were current on an in service type prior to retiring from full time service and that type is still being operated.
Sorry.
SL