S1E
Last comment on it, as I don’t want to derail the thread further.
I agree, it’s a vanishingly small chance of “no deal” grounding flights, however I have a small feeling something will be overlooked (“Paragraph 4, subclause b, section 4.2.4 part ii, which states no non-eu carrier can have aircraft insurance not based in the eu” or some other equal nonsense) that would ground flights for a period of time.
I’d put the chances of that happening the same as the unpronounceable Icelandic volcano blowing up again. Long odds, but not impossible.
Personally I’ll be waiting until closer to the time before booking holidays, but I’m cautious like that.