Yes - you can either travel from London Marylebone to Birmingham Moor Street or from London Euston to Birmingham New Street
No, there is no direct train from London to Athens.
Yes, Birmingham International station is linked to the airport, and you can get a train direct to Watford Junction.
It is a direct train in the new timetable, common sense prevails
No, you'd need to change at Birmingham New Street.
Yes there is.
By underground (tube).
The easiest ways are either to get the train from London Paddington (direct service with First Great Western) or take National Express coach 444 from London Victoria Coach Station.
Proably, outside of London Manchester Picadilly or Birmingham International then Birmingham New Street.
District Line (London Underground) from Hammersmith tube station to Victoria tube station.
Either the Megabus from Victoria or the train from Paddington
It's on the London Victoria line.
There is no such station as Liverpool Victoria. Do you mean Liverpool Lime Street?