Easiest to break up the RAF? Don't know NuLabour's real plan?
Sorry, but you assume that the RAF only does subordinate work for the other forces, when the reality is the RAF does startegic tasks completely divorced from the Army or Navy. The defence of UK airspace is just one example. Long-range interdiction and strategic bombing is another, though the latter could largely be handled now or in the near future by cruise missiles and drones. Splitting the RAF into land and naval air forces was how it all started, and would go horribly wrong. The RN has a long and disasterous history of not knowing how to specify or use aircraft, seeing them as an expensive option to buying more floating gin palaces. Whilst the RAF also has a jaded approach to providing pilots and aircraft for the RN, they at least want to provide them, even if they do want to largely control the result (such as the joint Harrier force).
Similarly, the Fishheads do an amount of work that is divorced from the Army or RAF, such as long-range maritime patrol in foreign waters, anti-piracy ops, and distant aid operations to remote islands. The latter does require heavy lift aicraft, but the first to arrive is usually naval craft in the area. And if the operation develops into mass evacuation the ships are required, and sometimes it is the only option when local airstrips have been either destroyed by a natural disaster or have fallen into the hands of undesireables.
The Army? Well, here the fun begins The Army actually has far too many roles to cover with the forces at their disposal, and does many operations where it does not need to co-operate with either the RAF or RN. Such tasks as close air support really do need foot sloggers as they are the only ones that can really get down in the mud and direct the aircraft in. The idea of an expanded Army Air-Co-Op unit completely separate from the RAF is good, as long as we don't go with some cripplingly stupid limitation like the Yanks did when they said "anything with wings is Air Force, anything with rotors is Army." But the idea of the Army running the whole RAF show sounds very bad.
No, all this is just political posturing before an election, there will be promises of a review, the election will come and go long before the review comes in. The idea of combining the three forces into two is just an attempt to look radical. The real NutLoon plan has always been to force our armed forces into a joint European force to replace the US-centric NATO. They have the hilariously naive idea that this will not only promote co-operation but somehow make the resultant force more efficient. In reality, it will just be another over-managed (by countless numbers of unaccountable euro beaurocrats) and unbalanced force, racked with inter-state squabbles over who funds what and what kit is bought from which member, and with any decision taking six months minimum of euro-wrangling and handwringing before anything concrete happens, if ever. Any resultant deployments will usually be too late and in the euro political gesture manner that sees UK troops getting dropped into firefights with even less prep or kit than they do now, and then unable to even communicate with the other troops in the areas because they won't be able to speak English.
The Fwenchies will insist on speaking Fwench, even if they can speak English; the Germans will want to show everyone what perfect English they think they can speak, even though they can't, and will thus never admit they don't understand what they're being told; the Italians will only want to speak to the female soldiers in the UK units; the Greeks will only want to speak to the men; the Spanish will only talk to ask to borrow kit whilst complaining about how unruly and poorly behaved our troops are; the Belgians will only speak if they are allowed to run every show, because they think they were once a great imperial power; the Dutch will be too stoned to talk sense to anyone; and any other member state will probably only send along a token force of administrators and other useless desk-warriors!
What we actually need is a drastic reappraisal of what we actually want our armed froces to do, followed up by some proper and serious spending to allow them to do the job in a balanced and co-operative manner. That will mean three individual armed forces, though the idea of a joint command stripping out some of the current individual command structures doesn't sound too bad. But I would suggest two combined commands - Defence of the UK and Foreign Operations - anything else just slot in below the two as required, with a cut-down top layer similar to the COBRA set up. The RAF would largely fall into the former whilst expanded FAA, Army Co-Op and a mix of cruise and drones (under Army control) could then handle the Foriegn bit. Some RN and Army units would have to go into the UK Defence role. For significant deployments against real foreign powers with an air force the RAF could lend some Defence forces fighter units to provide air CAP. Job done!