Airlines will tell you anything, before during or after the flight, but it depends when you ask as to what answer you get.
On another matter, I recently had the misfortune to suffer a four hour plus flight aboard a Thos Cook aircraft. The seat pitch was horrendous. I did the calcs and worked out the cost per seat to give each row an extra two inches of legroom was about £4 per seat/flight.
When I complained after the flight, the young lady calmly informed me that "The CAA stipulates the maximum seat pitch we can use." When I said, "Surely you mean minimum!" She corrected me, "No! It is definitely maximum." In the subsequent letter they did at least have it the right way round.
If my experience is anything to go by, unless you have a hip to knee measurement of less than fifteen inches, you are unlikely to fit into a Thos Cook aircraft.