Take Northern Line northbound to Leicester Square, then change for the Piccadilly Line northbound to get to King's Cross St. Pancras. I recomend that a change at Leicester Square is easier than at Euston.
the Saint-Pancras railway station has a direct link to Paris.
St. Pancras International is the train station directly next to the London Underground tube station of Kings Cross situated on the picadily line. There are clearly marked signs to direct you to and from both stations.
As there are no direct trains from Heathrow to London Waterloo, it's quicker to travel by underground from Heathrow on the Piccadilly Line to Leicester Square Underground Station and then change onto the Northern Line to London Waterloo Railway Station.
There are no direct trains from Nottingham to Heathrow. You need to go: - Nottingham to London St. Pancras - St. Pancras to Paddington (Underground, Circle line) - London St. Pancras to Heathrow. Alternatively, cheaper but slower: - Nottingham to London St. Pancras - St. Pancras to Heathrow (Underground, Piccadilly line)
The most direct path is east to the A201 south, across the Blackfriars Bridge to Southwark and then "The Cut" west to Waterloo Road. It is 6 minutes faster, on average, to use the A4200 due south across the Waterloo Bridge.
The Eurostar train service runs from St Pancras station in London direct to Paris (and beyond)
The underground line that connects St Pancras International to Russell Square is the Piccadilly Line. The journey typically takes just a couple of minutes, with direct trains available. Russell Square is located just a short distance from St Pancras, making it convenient for travelers heading to the British Museum or other nearby attractions.
It's complicated as there are no direct trains. Your best bet would be to take a train to Waterloo and then transfer on to the Underground.
There are no direct trains from Manchester Victoria to St Pancras. Use Manchester Piccadilly and go to London Euston, then a short walk or one tube stop along to St Pancras. Alternatively you can go from Manchester Piccadilly to Sheffield and change for St Pancras but that needs a ticket routed that way that may cost more and takes longer.
No. You need to take the Piccadilly Line tube from Heathrow to Piccadilly Circus, then onto the Bakerloo line to Waterloo Station. From Waterloo there is a direct South West Trains service to Exeter St Davids.
Well depends what time you go, it can usually be from £44 and above depending on what time you go. There's a direct service on the Midlands train, check the website out www.nationalexpresseastcoast.com
You don't. You travel from Sheffield to London by ordinary trains.