Thanks for the acknowledgements of 'savvy' organisership, in my opinion, nothing more than my event entrants should deserve!
In reality, all it took were a couple of phone calls and a drop in to the Barton Mills McD's to ask them. The first conversation for the A&S in May went something like this...
Me on the phnoe: "May I speak to a duty manager, please?"
McD: "Sure, no problem, one moment"
McD manager: "How may I help?"
Me: "I'm organising a mad cycling event that means cyclists will be passing thru Barton Mills between midnight and 3am, after your normal opening hours. I was wondering if you'd mind me advising them they can (or cannot) use the 24 hour drive through or click & collect"
McD: "Oh, I'm sure we can do better than that, can I take a few more details...?"
A couple of minutes later we had arranged for them to stay open until 3am on 8th May for the A&S. Similar for the G&YF until 4am on 11th June.
So sometimes all it takes is to ask and for there to be helpful staff to whom I am grateful