Hello!
There is no lounge at LCY, so don't feel too bad about that one! Everyone is in the same boat, flying Club or Traveller...!
Security at LCY has always been very quick for me, even at peak times, so I would not worry about that. Also, the security staff seem to be a lot more friendly and personable, again, in my experience that is.
The DLR is reliable, but make sure you check
www.tfl.gov.uk to make sure there are not any engineering works that may make your journey difficult as it is a holiday weekend.
Nice little airport, comfortable and pleasant with nice views over te ramp and runway to sit and have something to drink and watch.
Enjoy your flight.
BBB