Qantas lounge is much better anyways, just go straight there and ignore the BA one. Hopefully the refurb will make a lot of improvements.
I've had a better overall experience in SIN now I've started using SQ on my LHR-SIN trips - since the last wave of exec club 'enhancements' I decided to move my monthly trip away from BA metal towards a better onboard product with better food, cleaner planes, no stepping over people to go to the loo, modern IFE, etc, etc, etc. That's a recurring 70k+ GBP of revenue gone from 1 pax on 1 route alone.
The SQ lounge is ok, no CCR but way better than BA's SIN lounge; but you're generally only in there for an hour or so. The experience for the next 12 hours to LHR is a world of difference. And cheaper too, I find.