All the London railway stations :
Enfield Lock is on the Greater Anglia rail network, and is entirely accessible to wheelchair travellers.
Driver only operated services. Assistance at this station is provided by a staff member during ticket office opening hours.
See pictures and further accessible transport in London detail from links below.
National Rail : National Rail Greater Anglia
AccessAble Access Guide :
Accessibility friendly : This station appear to be fully accessible. There is a ramp to one of the platforms, and to cross platforms you need to exit the station and cross at the level crossing.
General description : See wiki
More comment : National Rail map & guide