http://www.semmms.info/140683/435117/fullschemedrawing
is the full A6MARR road scheme excluding complimentary measures on existing roads. You can see that the road doesn't properly tie-in to Ringway Road on this plan as the background is pre-upgrade and I understand that the Airport will be (or have) designed the tie-in themselves under the Airport City improvements.
The new 9000 space car park will be accessed from the 'other' bit of Rignway Rd from Styal Road which might not be ideal if you're coming from the Airport itself.
Also of note is the need for a new deck over the railway which will probably cause several closures of the railway whilst it's being built.
I'd be interested to see the current proposed road layout for Airport City as it seems to be changing as more detailed plans come forward.