I think there may be some confusion over FRADU - the Fleet Requirements & Air Direction Unit - I believe it to be the Hawk unit at RNAS Culdrose tasked with providing fast jet targets for a variety of roles in support of Naval training. To get a flying job there I'd expect you'd need to be an ex Military Fast Jet Pilot. I think that Serco have the contract to fly & maintain the FRADU Hawks.
Flight Refuelling Aviation Services are based at Bournemoth and fly the Falcon 20s (they may also still have a unit based at Teeside) also in support of military training, in particular they provide EW training and act as the "bomber" for Naval air defence training. A civilian pilot without military flying experience may be able to get work with FR. Contact Flight Refuelling.
FRADU and FR work together on Naval training - in particular the FRADU Hawks often fly in close formation with the FR Falcons to simulate a "bomber" with "missiles" under each wing. The "missiles" (Hawks) are launched and fly an anti-ship missile profile towards RN ships.