All the London railway stations :
Underground lines : Circle, District
Tower Hill station, not accessible - in May 2019
AccessAble Access Guide :
Accessibility friendly : Tower Hill is partially accessible to wheelchair. I found a lift at this station today, in May 2019. A member of staff informed me that there were still some issues as there are no ramps onto the trains, and therefore would not suit a small-wheeled vehicle.
Another tip, if wanting to access the Fenchurch station and C2C, take a short trip to the Tower Gateway station which is accessible by lift, and two stations travel onwards arrives at Limehouse. You do need to exit the DLR station to cross to the C2C lines, but there are lifts, albeit a tad small (June 2019). I will take pictures of this very soon.
Lift at Tower Hill, unsure which platforms it serves - May 2019
General description : Just by the Tower of London, and perfect for Fenchurch Street if you do NOT have any access issues.
More comment : Inclusive Britain Station Guide