Ivan,
If you read the document obtained by your own link, and look at the graph and table for ABC 14 on page 9, you will see that none of your contingency and headroom funding is available until FY17/18 (£345m) and significant funding only becomes available in subsequent years. Classic jam tomorrow which we will trumpet today.
Such a plan also assumes the "promise" of a 1% above inflation growth for the "equipment plan".
You have to plan on something, but whether this plan will actually be achieved?
First of all you have a possible (likely?) change of government. Then there is an SDSR with possible (likely?) changes in funding allocation. Then there are alternative uses for any "spare cash" (call it contingency/headroom or whatever) such as cost overruns (carriers, F-35, etc, etc), retention of equipment beyond planned retirement (Tornado, Sentinel), bringing UOR equipment into core funding, purchasing new equipment other than an MPA/MMA, etc, there's always something.....
Yes, under this plan there may be some money for new equipment (let's not even mention manpower or infrastructure) by about 2019, which might or might not be an MPA/MMA. But the important word in that sentence is "may".