score:9
There's no IST to TBS flight at 7:30PM. At least not on any day I can find. There is a daily SAW to TBS flight at 7:30PM between 03/26/17 and 10/28/17 and for that flight Turkish prescribes a four-five hour minimum connection time from IST, rightly so.
The Turkish website is misleading you (and no, the little (i) under IST doesn't display this, only the full details do):
Another Turkish website -- I landed here from Google Flights:
this site provides a lot less warnings.
Upvote:-2
A flight from London to Istanbul takes approximately 4 hours. The time difference between London and Istanbul is 3 hours. So the flight leaving at 11.30 should arrive at approximately 18.30. At least Skyscanner gives me this rough timetable. It might be possible that some of the sites you use still have the wrong timezones, as Turkey quite recently changed their timezone.