For train times, prices & how to buy tickets, just see https://www.seat61.com/Turk.... The video showcases an epic 3-night train journey from London to Istanbul, right across Europe to the edge of Asia, distilled into just 12 minutes...
The route takes you via Paris, Zurich, Zagreb, Belgrade & Sofia, with an evening in Belgrade and a day between trains in Sofia.
Quite a bit has changed since the video was made, so just see https://www.seat61.com/Turk... to learn about the latest train times, fares & tickets between London and Istanbul.
Channel The Man in Seat 61