All the London railway stations :
Canada Water is on the accessible Jubilee line, a route which includes stations such as London Bridge and Stratford. This station is also on the London Overground line (West Croydon to Highbury & Islington) where trains usually require a ramp to access trains if accessible at all.
Underground lines : Jubilee, London Overground (East London line)
AccessAble Access Guide :
Accessibility friendly : Yes. (A step 50mm/gap 70mm) & Bus Station.
Lift access between street and platform including London Overground services.
General description : See wiki
More comment :
British Rail Map & Guide - It maybe accessible, but there are no ramps or staff available. It most likely is accessible.
Inclusive Britain Station Guide