Originally Posted by scubainstructor87

I have done this a few times , different lounges and different airlines. Don't see any issues whatsover.

You don't have to be escorted out of T5A (that happens only once an hour, why wait). Just take the train to T5C, don't get off. on the way back it deposits you at passport control (if you wait for that hourly escort, you get deposited same place...)