http://realtimetrains.co.uk is a good website that gives you platform details too, among loads of other things.
Similar https://www.nationalrail.co.uk/times_fares/ldb.aspx
And open train times is for the deep nerds who like to "watch" their trains arrive...
@Squaredisk started
London Fixed Gear and Single-Speed is a community of predominantly fixed gear and single-speed cyclists in and around London, UK.
This site is supported almost exclusively by donations. Please consider donating a small amount regularly.
http://realtimetrains.co.uk is a good website that gives you platform details too, among loads of other things.