I suspect the E-3D fleet probably consider they are already adequately trained.
They certainly coped with the "High Boy" role in the Carribbean a few years back - as did the USAF AWACS types!
I guess it depends on what you want them to do? Provide a maritime surpic, comms relay with control of RW/FW aircraft, then that is AWACS 'bread and butter'. If you want low-level search, detection of periscopes, airborne delivery of survival gear and photography, then it's not.
As iRaven says, it provides some capability, but not all. Add C-130J into the mix when Afg ramps down and you might be there to cover LRSAR capability. How about a tie-up with the Irish Air Corps under an International MoU?
IIRC there was an option a few years ago to reduce the number of UK AWACS Crews for a few years and then to build them up again - has this started? Otherwise, it would be tricky to hold 24/7 standby and meet the NATO task (unless you could hold airborne standby under NATO's agreement).
CPL Clott