Hello from MAD,

If your profile's AA Gold = Ruby is accurate, then,
Fast track at MAD no, IB Lounge (at T4S, after passport control), yes
If possible get to MAD as early as possible to avoid the passport queues.

Not sure about if LHR T5 connections' fast track is open, if open then yes
https://www.flyertalk.com/forum/brit...lhr-t5-36.html