Get the Jubilee Line train to Baker Street and then the Metropolitan, Hammersmith & City or Circle Line to Euston Square.
Jubilee Line.
Yes, all London mainline stations have an underground station as well.
London, Euston and London, Victoria both have underground stations on the Victoria Line.The journey time is about 8 minutes.
The actual mainline station is all on one level (no steps or lifts). However, the underground station does not have lifts, but escalators instead.
Euston
It is about 3 miles from Liverpool Street to Euston.
Euston Railway Station in London, England, was built originally in 1837. As the United Kingdom's sixth busiest railway station, Euston Station was rebuilt and expanded from 1962 to 1968.
Like most journeys in London, the best way is to go by tube (underground) or you could take a cab.
The cost of a journey from Victoria Station to Euston Station on the London Underground typically ranges from £2.50 to £5.00, depending on the time of travel and whether you use an Oyster card or contactless payment. The journey is relatively short and falls within Travel Zone 1. Always check the latest fares, as they can change.
There is no mainline station at Heathrow. You would have to take the underground into London Euston and get a train from there. You will have to change trains at least once and the journey from Euston should take between 5 and 6 hours.
Euston
Euston