Fenchurch Street to Stepney East

While I don't know of any online information, I would strongly recommend you look for a book called 'Fenchurch Street to Barking' by J.E. Conor, published by Middleton Press. It gives a lot of information and has a lot of photos covering the whole area that it covers, and gives OS maps for each of the important areas, from many years ago. It is certainly a fascinating read. Another book by the same publishers, but written by Dr. Edwin Course, is called Barking to Southend, and is in the same style, ie mainly photos and OS maps, and covers the above route via Upminster, and includes some interesting historical photos as well. They are both still available to buy, or you may find them in your local library.

Does your local library have an online search and reserve facility? West Sussex CC has such a service, so the London boroughs may have. Always worth a try, could save vital funds.