Greater Anglia operates a train from Stratford to Colchester every 30 minutes. Tickets cost $23 - $35 and the journey takes 45 min. Alternatively, National Express operates a bus from Stratford to Colchester 4 times a day. Tickets cost $9 - $13 and the journey takes 1 h 40 min.
From Stratford (London) train to Colchester. 45 min £19. From London Stratford bus to Colchester. 1 h 40 min £8. From Stratford (London) train to Chelmsford City Centre, Bus Station (Chelm Bus Stn) then bus to Colchester Town Centre, Head Street (Colch Head St). 2 h 14 min £16. From Stratford drive to Colchester. 1 h 3 min £10.