So far the only coverage in Australia will be from BBC News and Sky News UK on Foxtel and Flash.
ABC News will probably have extensive updates during the day on the news channel, and have reportedly sent Casey Briggs to London (Antony Green is on a holiday booked prior to the election being called early).
For radio, BBC Radio 4 will have rolling coverage (via BBC Sounds), and the BBC World Service will have extensive coverage mixed with rest of the days global news (via BBC Sounds and SBS Radio).