We're going to Windsor castle first thing Thursday morning (May 31) at 9:00 am. Headed to Paris thereafter (like to arrive by 5-6 pm). We'll have a car from Sixt in Windsor. Options (1) Drop car in Heathrow, take Tube to St. Pancras, take Eurostar to Paris, (2) Drop car in Heathrow, fly to Paris, (3) Drive from Windsor to St. Pancras, take Eurostar to Paris. Priorities: (1) Engage in the Europe experience (I've only been to Europe once before), (2) Not stress out my mother in law (Me, wife, daughter, mother in law) too much. We would be taking a 2:30 train. Thinking that 11:30 departure from Windsor would give us enough time to get to St Pancras (by car) by 1 - 1:30. That's my preferred option. I haven't driven in England before - but I can keep a pretty cool head and be patient with traffic.
Is the timing too risky to push for the train ride (Option 3)? Simplest would be flying to Paris from Heathrow, but not much adventure there.