The Voyager conversion pales in comparison to the c.£2Bn estimated Carrier conversion cost (in 2012) for catapults and an arrestor system. AEW is already planned to be delivered by Crowsnest on the Merlin. Again, we seem to be conflating the subject of a future RAF requirement with the carrier. The RN's future requirements may lie in focusing their [equally] limited equipment budget on other ship programmes, especially as the Carrier Strike requirement is being delivered. Oh, and don't forget the RN want V-22 too. Money seems to grow on trees, it seems.
I'm confident that, should there be a desire for a UCAV to operate from QEC, a novel solution will be developed to launch and recover it.