Details on rail timetables and live departures and arrivals can be accessed from here (http://www.nationalrail.co.uk/ ).
You can look for live departures and arrivals in the “Live departures / Arrivals” box on this page. Timetables can be accessed via this page (http://www.nationalrail.co.uk/times_fares/timetables.aspx?_ga=2.98926686.1186244101.1548709617-1535911250.1548709606 ) or from the page of the train operator (e.g. for trains through Isleworth it would be the SouthWest Trains site (https://www.southwesternrailway.com/ ), which also shows the live departures / arrivals for their trains.
There are a number of commercial sites to book tickets on e.g. https://www.thetrainline.com/ .