Departure flight--How much time to allow at Heathrow terminal 5 for a departure on British Airways to Dublin--08:30 AM flight-- Sunday September 23--planning on tube, piccadilly line, Leichester Square to Heathrow Terminal 5--Thank you
For a 'domestic/interEuropean' flight like that, I allow 2 hours at Heathrow or most any large airport. You'll likely have time for breakfast, I usually do, but better safe than sorry. I can't tell you about your transport as I'm usually just walking over from the Sofitel Hotel.
You need to be at the airport two hours before your flight so set that alarm early!
On the Tube, it will take you about an hour to get from Leicester Square to Heathrow Terminal 5. You need to be at Heathrow 2 hours before your scheduled flight.
I thank each of you
To plan your Tube ride: https://tfl.gov.uk/
Heathrow is a complex of terminals so you should allow 15-30 minutes to get from the Tube to the appropriate part of Terminal 5.
I allow a minimum of 2 hours in addition to the time it takes getting to the airport.