Aidan I'm a regular Duxford visitor. There is good traffic management and you will probably be taken on a cross country route to the museum, not directly off the motorway at junction 10. The only time I've experienced serious traffic problems was for the BoB anniversary show in 2010 when everything went badly wrong and it was taking many hours to get in.As you are driving I would suggest arriving at Duxford by 10.00am
at the latest. The flying usually starts at 2.00pm but you'll find plenty to do and the flight line walk usually closes at midday and is something I like to do. You are in Bedfordshire I think so you won't have too far to go. I used to do some work for a company in Bedford itself and sometimes nipped over to Duxford for an afternoon
Depending on where you end up parked it might take you a while to get out. My membership gives me preferential parking at 'the bottom' near the exit, but if you end up at the top, by the land warfare museum, be prepared to wait a while, or eat a picnic whilst everyone else queues up.
The airfield is obviously open and quite exposed so even on a nice day in September a breeze can make it surprisingly chilly so be prepared!
I would have gone to this show, but unfortunately I'll be working up in Glasgow on Saturday night and won't make it back in time ):
Have a good one.
Steve