taking on AT/AAR should not be too much of a learning curve.
This simply shows how much you know about AT/AAR (ie, nothing). It is not a role anyone can simply 'assume' - the RAF has decades of expertise built up, particulary with Tac AT, that simply cannot be 'transferred' (not without the personnel, and 99% will tell you to go poke).
The RAF is an entire service that is 'air-focussed' - the Army are incapable of operating an effective air force because of their 'Soldiers First' philosophy. This serves their role very well, but will not serve air power. The RN thinks that ships are the be-all and end-all, and that everything can be launched off carriers - an airfield that can sink! Ships are slow and vulnerable (in relative terms) so do not fit very well into the modern, rapid acting 'expeditionary' environment. They are, however, very useful when you need to grandstand and project power (Gunboat diplomacy) - assuming that the 'enemy' have no modern air assetts capable of sinking them in minutes.
Forgive the possible naivety here, but exactly what was / is the RNs contribution in the face of a land-locked conflict such as Afghanistan? Ships are only good if you have water to sail them on, after all!
Let's also not forget that the RAF and RN do not merely support the great British squaddie on the sidelines - the SH and AT forces are largely dedicated to the support of land (and sea) based operations, but the FJ fleet is a fighting force in its own right that can be decisive (think Kosovo) - and the Army cannot fight and win sea battles (although the RAF could, in alot of cicumstances - a single Nimrod can carry enough armament to sink an entire carrier group in minutes). And there are few who can rival the capabilities of the RM.
In terms of the Venerable Irishman's comments, I have a much better suggestion: Let's leave the Flying to the RAF (and fund it properly), the sailing to the RN (and fund it properly) and the Soldiering to the Army (and fund it properly). We all do what we do they way we do it because we have all learned, within our own theatres of expertise, over a long time, that that is the BEST way to do it (given the available resources).