It's opposite Wood Street station which is on the National Rail line out of Liverpool Street.

But if you are at Stratford the best way is to get the Central Line to Leytonstone and the W16 bus from outside the station goes to Wood Street Station.

Or I see from LtS post above that you are near Maryland, then maybe best to get the 69 bus from there to the Bakers Arms and catch the W16 from there PM me if you need more detail.

More detail here

Wood Street station is one stop from Walthamstow Central on the Vistoria Line but it's always worth checking trains/tubes on Sundays in case of engineering work etc