Barbara says they were told they could change their departure to a different airport, since the schedule change was so significant. The next agent they talk to, if they choose to change, should confirm that.
If you want to use this as an opportunity to extend your trip and spend time in Ljubljana, Salzburg, Munich, or Vienna, now is your chance. We have done the train trips between Munich and Bled, and between Ljubljana and Vienna, and I can verify that the scenery is very nice, especially in Austria. So maybe a night each in Salzburg and either Munich or Vienna? Or one in Ljubljana and then on to one of the other cities?
Or perhaps you are satisfied with the suggestion by Carol now retired to stay with the current changed schedule and spend the overnight in the Heathrow Sofitel, with a daytime visit to Kew, Windsor, or other spot. We will be doing exactly that after our trip next September to the Dolomites—-flying out of Bologna at noon one day, overnight at Heathrow at the Sofitel, and British airways flight to Seattle the next morning. No stress.
I chose this option because we had such a bad experience with Venice airport after our Dolomites trip this past September (2022). We love Venice, but we never go in the summer due to crowds. But it was so close, and so tempting to have an afternoon in our favorite city and fly home the next day. Our afternoon and evening were indeed lovely, as we know how to avoid the crowds. I booked a hotel close to Piazzale Roma to make it easy to get to the airport, without battling crowds on the vaporetto. (I don’t care for the Alilaguna at all).
We arrived at the airport 2.5 hours ahead of our noon flight and it was chaos. The check-in desk was vastly understaffed (only one person working) and the very lengthy line was not moving at all. The security line was equally daunting. After 15-20 minutes of standing still, we decided to ditch some items and re-pack into our legal carry-on bags and head straight to security with the boarding passes on my phone. But the gates into the security area would not open with the boarding passes, and there was no staff available to help. After another 15-20 minutes of frustration, I got the gate to open with one of the passes, but then it wouldn’t let my husband through. Finally a staff person arrived at the security help desk and he went to explain the problem. They let him through and we finally got to the boarding gate, only to find our flight was delayed. We went back upstairs to the café to try to buy some food for lunch but the line was moving slowly, as the place was understaffed. Just as we neared the front of the line they called our flight for boarding, so we gave up.
After this experience my husband said we aren’t using Venice airport ever again. That’s OK—I prefer to travel into and out of Venice by train.