If you use airplane, you would arrive at either Sofia Airport or Varna Airport.

Metro services are now available.
Use the M2 line (Blue line), change trains at "Serdica" and get off at "Central" (Central Railway/bus Station).

    Sofia Airport     Sofia Metro 1, Sofia Metro 2, Sofia Metro 3     Central Bus Station Sofia

It takes 3 or 3.5 hours by bus.
This bus service is available at Central Bus Station Sofia.
    ETAP ADRESS / Group plus     BIOMET     UNION IVOKONI (only in Bulgarian)
    Time Table

All busses arrive at the bus station south of Veliko Tarnovo, which is about 500m far from the Hotel Etap. map
Since the road climbs up, it is better to take a taxi if you have a big bag.

There are also train service.   It takes about 4.5 hours
The Sofia station is near the Central Bus Station Sofia
From Sofia, you have to change trains at GORNA ORJAHOVICA.
    Bulgarian State Railway     Bulgarian Railway map     Information

It takes 3.5 or 4 hours by bus.
This bus service is available at Central Bus Station (avtogara) (only in Bulgarian) Map
    Varna Airport

Also, There are also train service.   It takes about 4 hours.
To Sofia: 07:15, 10:55, 13:25   need to change trains at GORNA ORJAHOVICA.

We have buses to Terminal 1 from Bus station South
    02:15, 03:45, 04:30, 09:00, 09:45, 12:30, 14:30, 21:15, 21:30
time table