The debate over UAV v Manned platforms has been discussed here before. There are still major issues with them which need to be resolved:
Where will we train with these things. Is there training airspace within the UK.
Is there enough of the RF spectrum available for use to be able to use them. Especially in a hostile EW environment. (The US were unable o use Hunter in GWII due to frequency clearance issues).
There are solutions to these issues but the technology is not yet mature (Laser comms etc).
Also shooting down a UAV is a measure the opposition would find an easier option during TTW, thus escalating the situation, and, as far as we are concerned means we do not achieve the mission.
There is obviously a balance to be struck, however, a manned platform capable of world wide, all weather, 24/7 operations with a range of ISR capabilities and effectors (Hard and soft kill) is a must.
Having flown many thousands of ISR hours over sea and land I am aware of the effects our platforms have by just being there. In addition we do as we do in war as we do on a daily basis day by day in peace.
The US MMA is the way forward and a large manned aircraft is the short to medium term solution (2030ish) is what we should be aiming for.