Looks all settled, I will be interested in Cascais & Rennes pireps !
Cascais is super easy and definitely GA friendly. Great starting point for exploring Portugal.
Well our trip didn’t go quite to plan as we had an avionics issue on the descent into Rennes, which turned it more into the Tour de France!
Rennes was “fine” for customs purposes with a few curiosities than could, but luckily didn’t cause issues. Despite the necessary PNR24 and a confirmation email customs did not show up. The normal procedure is to take a short walk from the GA parking on the Aeroclub to the main terminal and the customs office is located near to the passenger security point, however there was no one there either. Since we had a technical issue we were not in a rush and luckily spotted some Police while we were getting refreshments. They had more luck finding a Douane by going airside and banging on the office door. However, despite checking our passports they were insistent they didn’t need to be stamped (not correct). We then had to explain this to customs in Dinard and L2k later, both have said they will contact Rennes to update on post Brexit procedures!
Landing and parking for three nights came to Euro 38. No issues getting to or from the aircraft, if the Aeroclub are closed there is a buzzer on the gate which connects to a security office and they will release it remotely.
I can now at least claim to have spent some days in a country illegally 
I’m currently looking at clearing customs in Nantes since the PNR is still sensibly short at 2HR
@Whiskey_Bravo not sure if still planing the trip? I got confirmation from the PAF that it is ok to fly to/from Nantes internationally while being “handled” by aeroclub (no need to fork 250€ for Aviapartner, an exception versus Lille or Bergerac), you still have to walk yourself in & out of the main terminal, there is a “blue path” to follow to clear security & customs
If you have hi-vis, licence, passport then no need for personal escort by aeroclub, you still need their approval to come and they need to have a parking space for you in November, they will send forms & briefing packs
