quick point on the reference to widening the M56.
There are plans in place for further (ie over and above SEMMMS and Airport City changes) to road access. This includes improvements to the M56 and the 'Rainbow Works' that include improvement to the junction that serves the cargo area and Stennar Lane.
The need for these works will be triggered once the airport handles a certain number of passengers which, IIRC, is listed as a number per day and a certain number of days exceeding that threshold. It could be hourly throughput to be fair. I can't quite remember.