I agree about the lifts - I have for instance always found that the ones near the Charing X bridge at the RFH are never working and have ended up having to ask complete strangers to help get the buggy down two very long sets of steps. If someone was disabled they would not be able to access Charing X station or would be stuck on the railway bridge.
The problem is once a lift is installed, expectations of being able to use it will increase and I would also be concerned about people in wheelchairs getting stuck on Platform 2. The only option would be the Fire Brigade.
I worked on a social housing development near Excel in Docklands some years ago. A resident in a wheelchair was left on the DLR platform for several hours during the night as the lift was not working so he was stranded. He managed to shout loudly enough to wake up a local resident who called the Fire Brigade to rescue him. The chances of someone disabled getting off a train alone at night are probably slim at FH but its entirely possible during the day. This incident as well as my own experience with a disabled parent in a wheelchair, has made me very concerned about too much reliance being placed on lifts especially when they are external and in extensive use. There will always be someone who doesn't close the door properly hence preventing it working. There needs to be either a back up lift and /or second level access with the lift used as a back up- ie into and through Perry Vale car park. To proceed with one lift from either platform is very naive when it comes to the realities faced by physically challenged people.