Now sorted. It was due to a combination of things (in part how late it was!)
No locomotive was one cause as the descriptions weren’t that clear (but can be improved over time) so it wasn’t immediately clear to me that what I’d purchased was only a carriage.
Second issue was when joining tracks it can often looks like they’re joined but when you get in really close (not always easy on long runs) you see that actually they aren’t.
Thanks for everyones help, I’m off to get building and I hope the game goes from strength to strenth adopting a few of the suggestions on the forum (expanding stations to more than the original nomber of platforms and building double tracks in one go would be mine).