What are people using to book/look up train travel? I just tried to find a London to Belgrade route and absolutely none of the planners I found via DDG were cap

What are people using to book/look up train travel? I just tried to find a London to Belgrade route and absolutely none of the planners I found via DDG were capable. They'd all gladly sell me a pass, but none told me what station to leave/arrive from what time the trains were, etc.