Audio levels for SKY commercial

I'm creating a 20s commercial for broadcast and I have the following specifications for audio:
Audio Levels must adhere to BCAP rulings and be R128 compliant (Audio must be normalised at -23 LUFS +/- 1 LU).

I have no idea how that relates to the FCPX audio levels meter.

The audio consists of one Stereo Music track, which I have peaking at -6db at the moment but does anyone know if that's right. I don't want it to fail the QC!

Thanks,

You're gonna want some loudness metering for your mixes in the future if you're doing a lot of broadcast.
www.toneboosters.com/tb-ebuloudness/

This one does a lot too:
www.waves.com/plugins/wlm-loudness-meter

Thanks DC, I found a great plugin by Klangfreund, which does the job beautifully and was quite cheap I thought at only $49+VAT.
www.klangfreund.com/lufsmeter/

I second Klanggreund! I use it for TV shows on a weekly basis, have for a long time now. Very easy to set up and use, especially its Group function. Very worth while. Personally, I like it better than the Waves, less cluttered, less complicated, has auto adjusting and Groups that I find vital. Plus at a killer price. But use what works best for you.

Fantastic!