We can meet you at your Central London hotel or otherwise the tour would start just outside Caffe Nero (opposite Big Ben) and right next to the exit of Westminster Underground Station.
Alternatively we can finish at Marble Arch Station if we go on and see a final war memorial which is away from the others but well worth seeing.
The tour generally ends at the historic Hyde Park Corner which is full of things to see and explore and has a tube station for easy onward travel.
We can meet you at any Central London hotel, not just those listed. Then we'd walk or go by Underground to the tour starting point.