Channel 4 have live coverage of the World Championships. Walks are all on at 8 or 9 in the mornings, which unfortunately for UK walks fans is midnight or 1 am our time.
Mens 20K – 1 am Sunday 28 August
Womens 20K – 1 am Wednesday 31 August
Mens 50K – midnight Saturday 3 September (i.e very early Saturday morning)
It looks like they are also going to have highlights available, after each event, on the internet – here.